Adrenergic interactions in uterus and vascular smooth muscle in rats in vivo.
Simultaneous blood pressure and uterine responses to norepinephrine infusions were recorded in urethane-anesthetized, pentolinium-indomethacin treated rats in natural estrus under conditions in which no blockers or blockers of alpha 1-, alpha 2-, and beta-adrenergic receptors or of "reuptake" of norepinephrine were present. The contributions of alpha 1- and alpha 2-adrenergic receptors to the blood pressure response were similar during the initial portion of the response. At later times, however, alpha 1-adrenergic receptors were responsible for the major portion of the response. The tachyphylaxis of the pressor response that occurs during norepinephrine infusion could be prevented by preventing norepinephrine "reuptake" with imipramine. In the uterus, the initial small alpha-adrenergic contractile response (seen only at the lowest infusion rate) was quickly overwhelmed by a beta-adrenergic relaxing component. Administration of the beta-adrenergic receptor blocker, propranolol, during norepinephrine infusion caused similar increases in blood pressure in control, yohimbine-, and prazosin-treated rats. Uterine contractions, in contrast, were only significantly elevated during beta-adrenergic receptor blockade when yohimbine or imipramine had also been administered.
Gazis
D
D
Department of Physiology and Biophysics, Mount Sinai School of Medicine of CUNY, NY 10029.
Gonzalez
G
G
Mendlowitz
M
M
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D007262:Infusions, Intravenous; D009131:Muscle, Smooth, Vascular / Q000294:innervation / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000502:physiology*; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000294:innervation / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists