Abstract
The present study was designed to test the hypothesis that betamethasone may potentiate nitric oxide-mediated relaxation of coronary arteries of preterm lambs. Isolated coronary arteries were obtained from lambs delivered at 128 days gestation. The lambs were treated intramuscularly with a single dose of betamethasone or saline 48 h before delivery and were killed after 3 h of ventilation after delivery. Vessel rings were suspended in organ chambers filled with modified Krebs-Ringer solution (95% O2-5% CO2, 37 degrees C), and their isometric tension was recorded. The endothelium-dependent relaxation induced by bradykinin and calcium ionophore A23187 was greater in arteries from antenatal betamethasone-treated lambs than in arteries from control lambs. The relaxation was abolished by N omega-nitro-L-arginine. Nitric oxide induced a greater relaxation in vessels from antenatal betamethasone-treated lambs and in vessels preincubated with betamethasone than in vessels from controls. Coronary arteries from control and antenatal betamethasone-treated lambs relaxed similarly to 8-bromoguanosine 3',5'-cyclic monophosphate. Nitric oxide induced a greater increase in guanosine 3',5'-cyclic monophosphate content in coronary arteries from antenatal betamethasone-treated lambs than in arteries from control lambs. Our data suggest that antenatal betamethasone therapy potentiates nitric oxide-mediated relaxation in coronary arteries from preterm lambs, probably by affecting the activity of soluble guanylate cyclase of vascular smooth muscle cells.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: American Journal of Physiology-Heart and Circulatory Physiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.