Acute exposure to a low level of testosterone impairs relaxation in porcine coronary arteries

1. While the gender bias associated with coronary artery disease has been s uggested to be partially accounted for by the protective effects of oestrog ens, the role of testosterone remains unclear. The aim of the present study was to determine whether vasorelaxation could be affected by acute adminis tration of testosterone with and without 17 beta-oestradiol. 2. Precontracted porcine coronary artery rings were relaxed with sodium nit roprusside (SNP), levcromakalim, bradykinin (BK) or A23187, At 1 nmol/L, te stosterone impaired relaxations to BK and A23187, while the same concentrat ion of 17 beta-oestradiol potentiated levcromakalim- and SNP-induced relaxa tions, The impairment of relaxation responses by testosterone was reduced i n the presence of 17 beta-oestradiol, while the enhancement by 17 beta-oest radiol was decreased by testosterone. 3. We demonstrate that a low level of testosterone can impair agonist-induc ed relaxation, an effect that is reduced by 17 beta-oestradiol, This furthe r supports evidence indicating a detrimental role for testosterone in coron ary artery disease and suggests that circulating levels of testosterone may undermine the beneficial effects of oestrogen in women.