Oestrogen acutely caused relaxation in precontracted coronary and ear arteries, but caused additional contraction in thoracic aorta and pulmonary artery segments.
Does 17beta-estradiol acutely affect vascular tone differently across various isolated artery segments in adult male rabbits?
Estrogen has regional differences in its effect on vascular tone, causing relaxation in coronary arteries but vasoconstriction in the thoracic aorta and pulmonary artery.
The aim of the study was to assess how oestrogen acutely affects the tone of isolated artery segments from different vascular beds in rabbit. Cumulative concentrations of 17beta-oestradiol were added to ring segments of thoracic aorta, pulmonary artery, ear artery and coronary arteries from adult male rabbits. Coronary arteries precontracted with potassium or the thromboxane agonist, U46619, relaxed to oestrogen (10(-7) to 10(-4) M), whereas oestrogen (10(-8) to 10(-4) M) only caused additional contraction in segments of thoracic aorta and pulmonary artery precontracted with phenylephrine. In the thoracic aorta both the phospholipase C inhibitor NCDC (10(-4) M) and the cyclooxygenase inhibitor indomethacin (10(-5) M) almost completely blocked the contractile effect of oestrogen. In segments of the ear artery, oestrogen caused relaxation only at higher concentrations of oestrogen (10(-5) to 10(-4) M). In conclusion, oestrogen may cause both relaxation and vasoconstriction in different vascular beds, and in the thoracic aorta the contractile effects of oestrogen may be mediated via inositol phosphate-dependent pathways and release of prostaglandins.
Opgaard et al. (Thu,) reported a other. 17beta-oestradiol was evaluated on Vascular tone (relaxation or contraction). Oestrogen acutely caused relaxation in precontracted coronary and ear arteries, but caused additional contraction in thoracic aorta and pulmonary artery segments.