Autoradiographic characterization of beta-adrenoceptors in rat heart valve leaflets.
beta-Adrenoceptors were localized and characterized in valve leaflets of the rat heart. Sixteen micrometer-thick tissue sections containing the mitral and aortic valves were incubated with (-)3-[125I]iodocyanopindolol followed by autoradiography with computerized microdensitometry and comparison with 125I-labeled standards. beta-Adrenoceptors were present in all the valves studied. The selective beta 1-adrenoceptor antagonist CGP 20712 A (100 nM) displaced not more than 20% of the total binding sites, suggesting that most of the beta-adrenoceptors in the valve leaflets are of the beta 2-subtype. Forskolin-binding sites were detected in the mitral valve leaflet by incubation of adjacent tissue sections with [12-3H]forskolin. Our results indicate that catecholamines could regulate the function of the heart valves through stimulation of beta 2-adrenoceptors.
Pinto
J E
JE
Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland 20892.
Nazarali
A J
AJ
Torda
T
T
Saavedra
J M
JM
D000818:Animals; D001021:Aortic Valve / Q000378:metabolism*; D001345:Autoradiography / Q000379:methods; D001667:Binding, Competitive; D006651:Histocytochemistry; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D008943:Mitral Valve / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D007457:Iodine Radioisotopes; D011943:Receptors, Adrenergic, beta