Pharmacology of the human ovarian vein: responses to putative neurotransmitters and endothelin-1.

Abstract

An investigation of excitatory vascular responses in the human ovarian vein, a blood vessel normally exposed to high concentrations of ovarian steroid hormones and capable of adaptation to circulatory changes associated with reproductive life. Pharmacological responses of surgical specimens of human ovarian vein to electrical field stimulation of sympathetic nerves, noradrenaline, alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-MeATP), endothelin-1 (ET-1), and 5-hydroxytryptamine (5-HT) were studied. Comparisons were made between in vitro pharmacological responses and the diagnostic category, age, smoking status, reproductive history and hormonal status of patients. Research laboratory. Maximal contractile responses in longitudinal preparations, expressed as a percentage of the response to potassium chloride 125 mmol l-1, were 28% (SE 7.2) to electrical field stimulation and 107% (SE 15.1) to noradrenaline. In ring preparations, maximal responses to various agents were: noradrenaline 93% (SE 10.2); 5-HT 79% (SE 8.0); alpha,beta-MeATP 48% (SE 8.4); and ET-1 87% (SE 10.1). pD2(-log EC50) values for noradrenaline were 5.82 (SE 0.21) in longitudinal preparations and 5.65 (SE 0.10) in ring preparations; for ET-1 in ring preparations these values were 7.88 (SE 0.74). Responses to sympathetic nerve stimulation were attenuated by the adrenoceptor antagonist phentolamine; any residual responses were blocked by desensitisation of P2-purinoceptors with alpha,beta-MeATP or the addition of suramin, indicating that noradrenaline and adenosine 5'-triphosphate may be co-transmitters in these nerves. pD2 values for 5-HT were 5.97 (SE 0.12) in specimens from unsterilised patients (n = 19) compared with 5.20 (SE 0.24) in specimens from those who had previously undergone sterilisation (n = 6) (P < 0.05). No other relation between clinical characteristics and pharmacological responses were detected and, in particular, there were no apparent changes associated with ageing or hormonal status. Three main conclusions may be drawn from this study: (1) adenosine 5'-triphosphate is a co-transmitter in sympathetic nerves in the human ovarian vein; (2) tubal sterilisation affects vascular responsiveness to 5-HT; and (3) ovarian steroid hormones are likely to influence sympathetic vascular control via effects on catecholamine and adenosine 5'-triphosphate synthesis, storage, release, degradation or re-uptake, rather than via effects on vascular smooth muscle receptors.