Influence of prostaglandins on vasoconstrictor responses in the hindquarters vascular bed of the cat.
The effects of prostaglandins (PG), A1, A2, B2, E1, 6-keto-E1, F2 alpha and indomethacin on vascular resistance and vasoconstrictor responses were investigated in the feline hindquarters vascular bed under conditions of controlled flow so that changes in perfusion pressure directly reflect changes in vascular resistance. Infusion of PGE1, PGE2 and 6-keto-PGE1 (3 microgram/min) into the abdominal aorta significantly dilated the hindquarters vascular bed and inhibited vasoconstrictor responses to sympathetic nerve stimulation and intra-arterial injections of angiotensin, whereas hindquarters vasoconstrictor responses to tyramine and exogenous norepinephrine were unaffected. Infusion of PGA1, A2, B2 and F2 alpha at a similar rate produced transient changes in hindquarters vascular resistance and did not consistently alter vasoconstrictor responses to sympathetic nerve stimulation, angiotensin, norepinephrine and tyramine. Indomethacin in a dose which greatly attenuates the response to intravenous administration of arachidonic acid enhanced responses to nerve stimulation and norepinephrine. In addition, indomethacin had little or no effect on hindquarters perfusion pressure and systemic arterial pressure. These data suggest that E series prostaglandins possess the ability to modulate the actions of the sympathetic nervous system and angiotensin in the feline hindquarters vascular bed. In addition, these data suggest that PGEs, upon enzymatic conversion and dehydration to A and B series prostaglandins, lose their ability to consistently affect vasoconstrictor responses. Experiments with indomethacin further suggest that locally formed prostaglandins do modulate the effects of the sympathetic nervous system of the feline hindquarters.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D005260:Female; D006614:Hindlimb / Q000098:blood supply; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011453:Prostaglandins / Q000494:pharmacology*; D014439:Tyramine / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects*
D011453:Prostaglandins; D000804:Angiotensin II; D009638:Norepinephrine; D014439:Tyramine; D007213:Indomethacin