Time-Dependent Relationship Between Endothelial Dysfunction and High Blood Pressure in Fructose Drinking Rats.

Objectives: This study aims to investigate the duration required for endothelium dysfunction to develop in the fructose drinking-induced hypertension and examine the relative contributions of endothelium-dependent relaxing factors to changes in mesenteric arterial reactivity in male Wistar Albino rats.

Materials and methods: Metabolic parameters (water intake and food consumption) and hemodynamic parameters systolic blood pressure (SBP) and diastolic blood pressure (DBP)-were monitored in vivo. Vascular reactivity was examined in the isolated organ bath. Endothelium-dependent relaxation (EDR) to acetylcholine was observed in the absence and presence of pharmacological inhibitors of endothelial nitric oxide (NO) synthase, cyclooxygenase, and KCa2.3 channels. Contractile responses to phenylephrine and relaxation of sodium nitroprusside (SNP) were also determined.

Results: A significant increase in daily water intake and decrease in food consumption were typically observed in rats treated with 10% fructose for 4 weeks (p < 0.05). SBP and DBP increased significantly as early as 2 weeks of induction and continued to rise gradually throughout the induction period (p < 0.05). Fructose consumption significantly impaired EDR at week 3 and worsened at week 4 (p < 0.05). Impairment of the KCa3.1 channel-mediated component of endothelium-dependent hyperpolarisation (EDH)-type relaxation contributed to worsening EDR, whereas the contribution of NO-mediated relaxation was not apparent compared with the controls. The reduction in EDH-type relaxation in fructose-fed rats appears to be partially compensated by increased NO sensitivity in the smooth muscle region, as fructose induction increased SNP relaxation compared with the control.

Conclusion: These data provide evidence of early endothelial dysfunction developing concurrently with increased blood pressure in 10% fructose-fed rats. Decreased KCa3.1-mediated part of EDH-type relaxation appears to contribute to the impairment of endothelium-dependent vasorelaxation over time in this model.