{"title":"Molecular determinants of peptide and non-peptide binding to the AT1 receptor.","authors":"S S Karnik, A Husain, R M Graham","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>1. Several residues critically involved in AT1 receptor ligand-binding and activation have now been identified based on mutational and biochemical studies. 2. Asp281 and Lys199 of the rat AT1 receptor ion-pair with Arg2 and the Phe3 alpha-COOH of angiotensin II (AngII), respectively, and the Asp281/Arg2 interaction is critical for full agonist activity. 3. Agonist activity of AngII also requires an interaction of the Phe8 side chain with His256, which is achieved by docking of the alpha-COOH with Lys199. Non-peptide agonists interact with Lys199 and His256 in a similar fashion. 4. The crucial acid pharmacophores of AngII and the non-peptide antagonist, losartan, appear to occupy the same space within the receptor pocket. Binding of the tetrazole anion moiety of losartan involves multiple contacts, such as Lys199 and His256. However, this interaction does not involve a conventional salt bridge, but rather an unusual lysine-aromatic interaction. 5. Asp1 of AngII forms an ion-pair with His183, which stabilizes the receptor-bound conformation of AngII but is not critical for receptor activation. 6. These interactions and the involvement of other residues in stabilizing the wild-type receptor conformation or in receptor/G-protein coupling are considered here. 7. Despite these insights, considerable effort is still needed to elucidate how ligand binding induces receptor activation, what determines the specificity of AT1 receptor coupling to multiple G-proteins and the in vivo role of receptor down-regulation.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"3 ","pages":"S58-66"},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19955436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Transgenic rats: tools to study the function of the renin-angiotensin system.","authors":"M Bader, D Ganten","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>1. The development of the transgenic technology for the rat allowed the evaluation of gene functions in the cardiovascular system in vivo. New insights have been gained particularly in the functions of the renin-angiotensin system (RAS), as most transgenic rat models established so far carry genes of this system. 2. TGR(mREN2)27 is a rat harbouring the mouse Ren-2 gene and exhibiting fulminant hypertension. The plasma RAS in this animal is down-regulated; however, the tissue-specific production of angiotensin II is activated (e.g. in the adrenal gland, the brain and the vessel wall). The physiological consequences of this activation, which finally leads to hypertension, can be studied in TGR(mREN2)27, rendering it a valuable tool in the functional analysis of tissue RAS. 3. TGR(hREN) and TGR(hAOGEN) carry the human genes for renin and angiotensinogen, respectively. In these animals the species-specific interaction of the two proteins and the expression pattern of the genes can be studied. Furthermore, these animals can be used to test renin-inhibitory drugs for use in antihypertensive therapy. 4. Further refinement of transgenic methodology (e.g. by the development of gene targeting in rats), should enhance our understanding of the functions of the RAS in cardiovascular regulation.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"3 ","pages":"S81-7"},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19955439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Human type-1 angiotensin II (AT1) receptor gene structure and function.","authors":"K M Curnow","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>1. The type-1 angiotensin II (AngII) receptors, designated AT1, mediate most of the biological actions of the peptide hormone AngII. They are the most recent drug target for the treatment of hypertension and cardiac failure and basic research is now focusing on the mechanisms that regulate their expression. 2. In humans there is a single AT1 gene. It encodes a 47 kb pre-mRNA containing five exons, with the previously described AT1 open reading frame (ORF) on exon 5. Alternative splicing results in the production of mature mRNA that are translated at different efficiencies and encode two receptor isoforms. The inclusion of exon 2 markedly inhibits translation of the down-stream ORF, both in vitro and in vivo. Nonetheless, this exon is present in up to one-half of AT1 mRNA in all tissues studied. 3. Transcripts containing exon 3 spliced to exon 5 encode a receptor with an amino-terminal extension of 32 amino acids and represent up to one-third of total AT1 mRNA in each tissue examined. In vitro, these latter transcripts are translated to produce a longer receptor and, in transfected cells, they encode a functional AT1 receptor with ligand-binding and signalling properties similar to those of the short isoform. 4. Exon 4 is of minor significance as it is rarely spliced into AT1 mRNA. 5. These data indicate that, in addition to characterizing factors that modulate AT1 promoter activity and RNA stability, it is important to analyse the splicing patterns of this gene when studying the regulation of its expression.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"3 ","pages":"S67-73"},"PeriodicalIF":0.0,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19955437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H Kino, J Hama, T Takenaka, K Sugimura, K Kamoi, S Shimada, Y Yamamoto, S Nagata, T Kai, M Horiuchi
{"title":"Effect of an angiotensin II receptor antagonist, TCV-116, on neointimal formation following balloon injury in the SHR carotid artery.","authors":"H Kino, J Hama, T Takenaka, K Sugimura, K Kamoi, S Shimada, Y Yamamoto, S Nagata, T Kai, M Horiuchi","doi":"10.1111/j.1440-1681.1995.tb02954.x","DOIUrl":"https://doi.org/10.1111/j.1440-1681.1995.tb02954.x","url":null,"abstract":"<p><p>1. In the present study, we examined the effect of a novel angiotensin II type I receptor antagonist, TCV-116, on carotid neointimal formation after balloon injury in SHR and WKY rats. 2. Oral administration of TCV-116 at a dose of 10 mg/kg per day reduced not only systolic blood pressure but also neointimal formation after carotid balloon injury. TCV-116 also suppressed cardiac hypertrophy. An angiotensin-converting enzyme inhibitor, lisinopril (20 mg/kg per day), had a similar effect to that of TCV-116. 3. In the WKY experiment, both TCV-116 and lisinopril suppressed neointimal formation as well as systolic blood pressure, but did not suppress cardiac hypertrophy. 4. Although SHR showed markedly enhanced neointimal formation after balloon injury compared with age-matched WKY rat, both TCV-116 and lisinopril showed similar suppressive effects on neointimal formation in both SHR and WKY rats. 5. These results confirm the important role of angiotensin II in neointimal formation following balloon injury. Further studies are needed to clarify the mechanism of the difference between SHR and WKY rats in the response of vascular smooth muscle cells.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S360-2"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1440-1681.1995.tb02954.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20027033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effects of benidipine, a long-acting calcium antagonist, on renal functions in anaesthetized spontaneously hypertensive rats.","authors":"H Nomura, H Kusaka, A Karasawa","doi":"10.1111/j.1440-1681.1995.tb02943.x","DOIUrl":"https://doi.org/10.1111/j.1440-1681.1995.tb02943.x","url":null,"abstract":"<p><p>1. The effects of benidipine, a long-acting calcium antagonist, on renal functions were determined in anaesthetized spontaneously hypertensive rats (SHR), as compared with those of amlodipine. 2. Benidipine at 3 and 10 mu g/kg (i.v.) significantly increased urine volume, sodium (Na) and potassium (K) excretions with no change in creatinine clearance (C-CRE). The increase in K excretion was relatively slight. Benidipine increased p-amino-hippuric acid clearance (C-PAH) without any change in C-CRE and, thus, decreased filtration fraction (FF). 3. On the other hand, amlodipine at 300 mu g/kg (i.v.) significantly increased Na and K excretions, but did not change FF. 4. Thus benidipine, but not amlodipine, can dilate glomerular efferent arteriole as well as afferent arteriole in SHR. It is, therefore, expected that benidipine would not induce intraglomerular hypertension, which could result in the progression of glomerular injury. 5. Benidipine at 3 mu g/kg (i.v.) increased lithium clearance, while it decreased CRE concentration and increased Na concentration in the stop-flow urine from the distal tubule. 6. These results suggest that benidipine produces diuresis by the inhibition of water and Na reabsorption at both the proximal and the distal tubules.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S335-6"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1440-1681.1995.tb02943.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20027125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T Yoshimoto, M Naruse, K Naruse, Y Fujimaki, A Tanabe, T Muraki, H Hagiwara, S Hirose, H Demura
{"title":"Gene expression of vascular natriuretic peptide receptor in the aorta of hypertensive rats.","authors":"T Yoshimoto, M Naruse, K Naruse, Y Fujimaki, A Tanabe, T Muraki, H Hagiwara, S Hirose, H Demura","doi":"10.1111/j.1440-1681.1995.tb02870.x","DOIUrl":"https://doi.org/10.1111/j.1440-1681.1995.tb02870.x","url":null,"abstract":"<p><p>1. To elucidate the pathophysiologic role of vascular natriuretic peptide (NP) receptor in hypertension, we determined NP-A and NP-B receptor mRNA levels by means of ribonuclease protection assay in aorta of three types of hypertensive rats. 2. The NP-A receptor mRNA level was higher in stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and deoxycorticosterone acetate-salt hypertensive rats than that in their respective control rats. On the contrary, the NP-A receptor mRNA level was lower in NG-nitro-L-arginine-methyl ester (L-NAME)-induced hypertensive rats compared with that in the control. 3. The NP-B receptor mRNA level did not show any significant change in all three hypertensive rats compared with their respective controls. 4. The present study suggests that high blood pressure is not the major factor regulating the NP receptor gene expression and also that the receptor subtype is independently regulated from each other.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S175-6"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1440-1681.1995.tb02870.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20027234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Proceedings of the 8th International Symposium on SHR and Related Studies. Osaka, Japan, 18-20 October 1994.","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S1-379"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20028022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effects of gamma-aminobutyric acid on regional vascular resistances of conscious spontaneously hypertensive rats.","authors":"Y Takemoto","doi":"10.1111/j.1440-1681.1995.tb02839.x","DOIUrl":"https://doi.org/10.1111/j.1440-1681.1995.tb02839.x","url":null,"abstract":"<p><p>1. The regional vascular effects of a central injection of gamma-aminobutyric acid (GABA) in conscious spontaneously hypertensive rats (SHR) were compared with normotensive control rats (NCR), including Wistar-Kyoto rats (male, 10-20 weeks of age). One week or more after insertion of a cannula into the cisterna magna, an electromagnetic flow probe was implanted around one of five arteries, and a catheter for measurement of blood pressure and heart rate was inserted into the terminal aorta or common carotid artery. Cardiovascular changes were observed in the conscious animal after recovery from the surgery. Peripheral resistance was calculated as pressure divided by flow. 2. Ten min following intracisternal injection of 10 mu mol of GABA, mean arterial pressure and heart rate were significantly lowered (P < 0.05; t-test): - 29 and -16% (70 d.f.) in SHR versus -23 (116 d.f.) and -19% (112 d.f.) in NCR. Hindquarters, carotid, superior mesenteric and renal, but not coeliac, vascular resistances were significantly lowered (P < 0.05; t-test, 21, 9, 18 d.f.) in SHR. However, when comparing the effect of GABA injection in SHR and NCR, there were no significant differences in coeliac, carotid and hindquarters vascular resistances, but there were significant decreases in superior mesenteric and renal vascular resistances in SHR. 3. These results indicate that: (i) a cisternal injection of GABA in SHR decreases both peripheral vascular resistance and heart rate, and thereby lowers blood pressure; (ii) the vascular resistance of the superior mesenteric and renal vascular beds was more decreased in SHR than in NCR. This suggests that the GABAergic control of regional vascular resistance differs in the SHR and the NCR.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S102-4"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1440-1681.1995.tb02839.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20028026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K Tsuda, Y Minatogawa, H Iwahashi, I Nishio, R Kido, Y Masuyama
{"title":"Spin-labelling study of biomembranes in spontaneously hypertensive rats: calcium- and calmodulin-dependent regulation.","authors":"K Tsuda, Y Minatogawa, H Iwahashi, I Nishio, R Kido, Y Masuyama","doi":"10.1111/j.1440-1681.1995.tb02897.x","DOIUrl":"https://doi.org/10.1111/j.1440-1681.1995.tb02897.x","url":null,"abstract":"<p><p>1. The present study was performed to investigate alterations in membrane characteristics of spontaneously hypertensive rats (SHR) by using an electron paramagnetic resonance (EPR) and spin-labelling methods. 2. Washed erythrocytes from SHR were examined and compared with erythrocytes from age-matched normotensive Wistar-Kyoto (WKY) rats. 3. The values of outer hyperfine splitting (2T' 11) and that of the order parameter (S) obtained from EPR spectra for a spin label agent (5-nitroxide stearate) were significantly higher in the erythrocytes of SHR than in those of WKY rats. 4. When calcium (Ca2+) was loaded to erythrocytes with a Ca2+ ionophore (A 23187), the order parameter (S) of the EPR spectra showed a greater increase in SHR than in WKY rats. Furthermore, the Ca2+ -induced change in the order parameter (S) of SHR was significantly antagonized by pretreatment of the Ca2+ antagonists (verapamil, diltiazem) and a calmodulin antagonist (W-7). 5. The results show that the erythrocyte membranes of SHR tolerated different spin motions from those of normotensive WKY rats in the EPR study, which might be associated with the idea that the membrane fluidity might be lower in SHR. Furthermore, the data suggest that Ca2+ -calmodulin antagonists may ameliorate the Ca2+ -induced changes in membrane functions in hypertension.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S234-6"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1440-1681.1995.tb02897.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20028030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"What is the difference of bone growth in SHR and SD rats?","authors":"T Inoue, A Moriya, K Goto, T Tanaka, M Inazu","doi":"10.1111/j.1440-1681.1995.tb02900.x","DOIUrl":"https://doi.org/10.1111/j.1440-1681.1995.tb02900.x","url":null,"abstract":"<p><p>1. Both sexes of spontaneously hypertensive rats (SHR) and Sprague-Dawley (SD) rats were used in this study. 2. At 6, 12, 18, 24, 30, 36, 42, 48, 54 and 60 weeks old, tibia length (L), volume (V), dry weight (DW), bone mineral density (BMD) in tibia and serum biochemical parameters (Ca2+, Ca, iP, ALP, TRAP) were measured. 3. At the 18 and 48 weeks old, bone morphometry was performed (mineral apposition rate, trabecular bone volume and trabecular thickness). Serum PTH and osteocalcin level were determined in 18 week old rats. 4. The time course change of DW, L and V were almost the same as the trends of bodyweight in each group, namely, male SD had the highest value, female SD and male SHR showed the same value and the lowest figures were obtained in female SHR. 5. BMD of the middle area showed almost the same trends with the time course change of bodyweight. On the other hand, both sexes of SHR had lower BMD than that of SD in the proximal area. 6. Serum biochemical parameters showed the same trends in both sexes of SD and SHR except for ALP (a marker of bone formation) which was higher in male than in female rats. 7. Mineral apposition rate, trabecular bone volume and trabecular thickness were not different between the same sex of SD and SHR. 8. These findings suggest that trabecular bone in SHR had a lower mineral status than that of SD rats not only in the adult but also in the young. This alteration may due to the abnormal mineralization mechanisms.</p>","PeriodicalId":75710,"journal":{"name":"Clinical and experimental pharmacology & physiology. Supplement","volume":"22 1","pages":"S242-3"},"PeriodicalIF":0.0,"publicationDate":"1995-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1440-1681.1995.tb02900.x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20028033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}