Role of endothelium in the vasodilating effect of progestins and androgens on the rat thoracic aorta.
1. In the rat thoracic aorta, contractions induced by noradrenaline were inhibited by the steroids progesterone, pregnanolone, testosterone and 5 alpha- and 5 beta-dihydrotestosterone. 2. Removal of endothelium did not prevent relaxation to the steroids, suggesting that the vasodilating effect of steroids occurred on the smooth muscle cells. 3. gamma-Aminobutyric acid (GABA) did not modify noradrenaline-induced contraction. Thus, the vasodilation elicited by steroids is not apparently mediated by GABA receptors. 4. On the basis that noradrenaline opens receptor-operated calcium channels to induce contraction, we suggest that relaxation by steroids involves a blockade of this type of channels.
Perusquía
M
M
Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City.
Hernández
R
R
Morales
M A
MA
Campos
M G
MG
Villalón
C M
CM
D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011372:Progestins / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000728:Androgens; D011372:Progestins; D014662:Vasoconstrictor Agents; D005680:gamma-Aminobutyric Acid; D009638:Norepinephrine