Alpha-adrenergic receptors in human myometrium during pregnancy.
The distribution and mechanisms of alpha-adrenergic receptors have been studied in myometrial preparations from women delivered by cesarean section at term. With the use of the radioligand tritiated dihydroergocryptine, the number of alpha-adrenergic receptors was 210 fmol/mg of protein in the uterine fundus and 195 fmol/mg of protein in the lower uterine segment. Competition experiments showed that 60% of the alpha-adrenergic receptors had properties as alpha 1-adrenergic receptors and 40% as alpha 2-adrenergic receptors. In vitro tension studies verified the existence of physiologically active alpha 1- and alpha 2-adrenergic receptors in the myometrial preparations. alpha 2-Adrenergic receptor stimulation resulted in lowered levels of intracellular cyclic adenosine monophosphate. The intracellular cyclic adenosine monophosphate was further reduced by additional alpha 1-adrenergic receptor stimulation, probably secondary to an activation of calcium-calmodulin-dependent phosphodiesterase.
Berg
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Andersson
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Ryden
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D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D001667:Binding, Competitive; D002118:Calcium / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D004088:Dihydroergotoxine / Q000378:metabolism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009215:Myometrium / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011247:Pregnancy; D011942:Receptors, Adrenergic, alpha / Q000032:analysis* / Q000145:classification / Q000502:physiology; D014590:Uterine Contraction / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D004088:Dihydroergotoxine; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D002118:Calcium; D009638:Norepinephrine