Relaxation effect of estradiol on different vasoconstrictor-induced responses in rat thoracal artery.
This experiment was designed to compare the relaxant effect of estradiol on the contractions induced by 5-hydroxytryptamine, phenylephrine, and KCl in absence or presence of preincubation with the nitric oxide synthase inhibitor (NOS) N (omega)-nitro-L-arginine methylester (L-NAME). R at thoracic aorta contraction responses to vasoconstrictors were observed in the absence or presence of L-NAME. 17beta-Estradiol was added in increasing cumulative concentrations in the absence or presence of the L-NAME when the contractile response had reached a stable plateau. In the presence of L-NAME, 10(-6) M estradiol on precontracted 5-hydroxytryptamine rings caused significant relaxation in comparison with precontracted phenylephrine, KCl rings. In the presence of L-NAME, 10(-5) M and 10(-6) M estradiol doses on precontracted 5-hydroxytryptamine rings showed no significant difference in relaxation. The 10(-6) M, 10(-5) M, and 10(-4) M estradiol doses on precontracted phenylephrine caused concentration dependent relaxations. The results of this study show that acute vasorelaxation to 17beta-estradiol is largely mediated via NO-independent pathways by inhibiting Ca+2 influx from the extracellular space and Ca+2 released from intracellular stores.
Dursun
Nurcan
N
The Physiology Department, Erciyes University, Medical Faculty, 38039-Kayseri, Turkey. dursun@erciyes.edu.tr
Arifoglu
Canan
C
Süer
Cem
C
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D013895:Thoracic Arteries / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009569:Nitric Oxide; D012701:Serotonin; D004958:Estradiol; D011189:Potassium Chloride; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester