Sex differences in nitric oxide-mediated attenuation of vascular reactivity to vasopressin are abolished by gonadectomy.

Sex differences in nitric oxide-mediated attenuation of vascular reactivity to vasopressin are abolished by gonadectomy.

Stallone J N

European journal of pharmacology

1994

1994-07

In the rat thoracic aorta, contractile responses to vasopressin are two-fold higher in females than in males, primarily because nitric oxide-mediated attenuation of contraction is greater in males than in females. To determine the role of the gonadal steroids in this phenomenon, the effects of gonadectomy on nitric oxide and vascular reactivity to vasopressin were examined in thoracic aortae of age-matched intact and gonadectomized male and female rats. Maximal response to vasopressin was markedly higher in gonadectomized-male than in intact-male aortae (2729 +/- 421 vs. 1375 +/- 222 mg/mg ring weight; P \textless 0.01). Inhibition of nitric oxide synthase with NG-methyl-L-arginine (L-NMMA, 250 microM) enhanced maximal response of intact-male (2824 +/- 413 mg/mg ring weight; P \textless 0.01) but not gonadectomized-male aortae (3034 +/- 365 mg/mg ring weight; P \textgreater 0.05). Sensitivity of male aortae to vasopressin was unaffected by gonadectomy or

*Orchiectomy; *Ovariectomy; Acetylcholine/pharmacology; Animals; Aorta; Arginine/analogs & derivatives/pharmacology; Female; In Vitro Techniques; Male; Muscle; Muscle Contraction/drug effects; Nitric Oxide/antagonists & inhibitors/*physiology; omega-N-Methylarginine; Phenylephrine/pharmacology; Potassium Chloride/pharmacology; Rats; Sex Characteristics; Smooth; Sprague-Dawley; Thoracic/drug effects/physiology; Vascular/drug effects/*physiology; Vasopressins/*pharmacology

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