Intramural coronary artery constrictor reactivity to thromboxane is higher in male than in female rats

Abstract

Background. The prevalence of cardiovascular disorders is higher among men than in age-matched women. This is probably related, in part, to gender-dependent differences in coronary function including thromboxane-A2 (TXA2) sensitivity. This question has been examined only on major, epicardial coronaries. The intramural small arteries directly responsible for supplying the myocardial arterioles with blood have been hardly accessible for investigation, owing to difficulties in their preparation. Vasoconstrictor TXA2 excess generated by platelets and the vascular wall may play an important role in coronary ischemic events. In the present study we tested the vasoconstrictor reactivity of intramural coronary arteries to TXA2.Methods. Secondary, intramural branches of the left anterior descendent coronary artery of Sprague–Dawley rats (diameter: 200 μm) were placed into a vessel chamber. TXA2 vasoconstrictor reactivity was measured on the basis of pressure–diameter curves in normal Krebs–Ringer solution and after addition of TXA2 receptor agonist.Results. Vasoconstrictor response induced by TXA2 agonist was twice as strong in males compared with females for the whole pressure range ( p < 0.001).Conclusions. A gender-dependent difference was demonstrated in TXA2-induced contraction of intramural coronary artery segments. In some pathologic situations the enhanced TXA2 release from platelets and injured vascular wall may cause greater vasoconstriction of intramural coronary arteries in males than in females.