Comparative study of mechanical responses of hepatic arteries strips to adrenalin in presence of pyridoxine and pyridoxal-5'-phosphate.

Since it is known that PLP inhibits "in vitro" the COMT much more than pyridoxine; the influence of pyridoxine to the response of hepatic arteries isolated to AD has been compared to the influence of PLP to the same arteries. As for as the increase in percent is concerned, the result is that PLP gives rise to a greater answer to AD than pyridoxine. Such effects lacked when pyrogallol, a powerful COMT inhibitor, was present. Taking such results as a basis, it has been concluded that the mechanism of action of pyridoxine and of PLP was metabolic and that it was based on the COMT inhibition, even for the hepatic arteries. It was been also deduced that the higher efficiency of PLP compared to the pyridoxine's was due to its greater capacity to inhibit the COMT.