title: Gender differences in biomechanical properties of intramural coronary resistance arteries of rats, an in vitro microarteriographic study.
abstract: The prevalence of ischemic heart disease is lower in premenopausal females than in males of corresponding age. This should be related to gender differences in coronary functions. We tested whether biomechanical differences exist between intramural coronary resistance arteries of male and female rats. Intramural branches of the left anterior descending coronary artery (uniformly approximately 200microm in diameter) were isolated, cannulated and studied by microarteriography. Intraluminal pressure was increased from 2 to 90mmHg in steps and steady-state diameters were measured. Measurements were repeated in the presence of vasoconstrictor U46619 (10(-6)M) and the endothelial coronary vasodilator bradykinin (BK) (10(-6)M). Finally, passive diameters were recorded in calcium-free saline. A similar inner radius and a higher wall thickness (41.5+/-2.9microm vs. 31.4+/-2.7microm at 50mmHg in the passive condition, p<0.05) resulted in lower tangential wall stresses in male rats (18.9+/-1.9kPa vs. 24.9+/-2.5kPa at 50mmHg, p<0.05). Isobaric elastic modulus of vessels from male animals was significantly smaller at higher pressures. Vasoconstrictor response was significantly stronger in male than in female animals. Endothelial relaxations induced by BK were not different. This is the first demonstration that biomechanical characteristics of intramural coronary resistance arteries of a mammalian species are different in the male and female sexes. Higher wall thickness and higher vascular contractility in males are associated with similar endothelial function and larger high-pressure elasticity compared to females. These gender differences in biomechanics of coronary resistance arteries of rats may contribute to our better understanding the characteristic physiological and pathological differences in humans.
authors.affiliation: Institute of Human Physiology and Clinical Experimental Research, Faculty of Medicine, Semmelweis University, Budapest, Hungary. matraim@freemail.hu
authors.forename: Mate
authors.initials: M
authors.lastname: Matrai
authors.forename: Metin
authors.initials: M
authors.lastname: Mericli
authors.forename: Gyorgy L
authors.initials: GL
authors.lastname: Nadasy
authors.forename: Maria
authors.initials: M
authors.lastname: Szekeres
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Varbiro
authors.forename: Ferenc
authors.initials: F
authors.lastname: Banhidy
authors.forename: Nandor
authors.initials: N
authors.lastname: Acs
authors.forename: Emil
authors.initials: E
authors.lastname: Monos
authors.forename: Bela
authors.initials: B
authors.lastname: Szekacs
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000502:physiology* / Q000503:physiopathology; D004548:Elasticity; D005260:Female; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D014661:Vasoconstriction