[Effects of oxygen free radicals on myocardial alpha 1-adrenoceptor and its subtypes in rat].
The effects of oxygen free radicals on myocardial alpha 1-adrenoceptor and its subtypes and beta-adrenoceptor were observed by the method of radioligand binding assay in rat. The experiments showed: (1) .OH and O??? reduced the Bmax of alpha 1-adrenoceptors binding to 125IBE2254 by 55% and 36%, respectively. (2) The KI values of alpha 1-adrenoceptors were increased by .OH (by 171%), but not by O2-. (3) Both .OH and O2-. increased the ratio of alpha 1A vs alpha 1B subtypes. (4) beta-adrenoceptors were not changed by either .OH or O2-. (5) Oxygen free radical scavengers mannitol and superoxide dismutase were capable of preventing the changes of alpha 1-adrenoceptor and its subtypes induced by oxygen free radicals. The above results suggest that oxygen free radicals can reduce the number and affinity of myocardial alpha 1-adrenoceptors, of which the alpha 1B subtype is more accessible to the changes.
Gong
H B
HB
Institute of Vascular Medicine, Third Hospital, Beijing Medical University.
Han
Q D
QD
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers; D005609:Free Radicals; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification* / Q000378:metabolism
D002121:Calcium Channel Blockers; D005609:Free Radicals; D018340:Receptors, Adrenergic, alpha-1; D010100:Oxygen; D002118:Calcium