title: Characterization of beta adrenergic receptors in human cerebral arteries and alteration of the receptors after subarachnoid hemorrhage.
abstract: The nature of beta adrenergic receptors in human cerebral arteries was characterized and alteration of these receptors after subarachnoid hemorrhage was examined using a radioligand binding assay. The specific 3H-dihydroalprenolol, a beta adrenergic antagonist, binding to human cerebral arteries was saturable and of high affinity (KD = 12.3 nM) with a Bmax of 790 fmol/mg protein. Ki values and Hill coefficients of adrenergic agents for 3H-dihydroalprenolol were as follows; propranolol, 4.1 X 10(-8)M, 1.01; isoproterenol, 1.7 X 10(-6)M, 0.80; epinephrine, 8.3 X 10(-6)M, 0.48; norepinephrine, 2.3 X 10(-5)M, 0.45; metoprolol, 6.8 X 10(-8)M and 7.9 X 10(-6)M, 0.62; butoxamine, 2.2 X 10(-8)M and 2.1 X 10(-6)M, 0.43. The analysis of inhibition of specific 3H-dihydroalprenolol binding by these adrenergic agents suggests that human cerebral arteries contain a high density of beta adrenergic receptors and that the receptors are classified into two types, namely beta 1 and beta 2 adrenergic receptors. The calculated beta 1/beta 2 ratio from Hofstee plots was approximately 4/6. KD and Bmax of 3H-dihydroalprenolol binding to the cerebral arteries after subarachnoid hemorrhage were compared with those of control group. KD and Bmax of 3H-dihydroalprenolol binding of subarachnoid hemorrhage group were 13.9 nM and 1140 fmol/mg protein, respectively. The calculated beta 1/beta 2 ratio was approximately 6/4. These data suggest that the density of total beta adrenergic receptors increased without any significant change in the affinity after subarachnoid hemorrhage and that the increase of beta 1 adrenergic receptors was dominant.
mesh_terms: D000070:Acebutolol / Q000378:metabolism; D000328:Adult; D000368:Aged; D000420:Albuterol / Q000378:metabolism; D002078:Butoxamine / Q000378:metabolism; D002536:Cerebral Arteries / Q000378:metabolism*; D004082:Dihydroalprenolol / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008433:Mathematics; D008790:Metoprolol / Q000378:metabolism; D008875:Middle Aged; D009638:Norepinephrine / Q000378:metabolism; D011433:Propranolol / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013345:Subarachnoid Hemorrhage / Q000378:metabolism*
chemical_list: D011943:Receptors, Adrenergic, beta; D002078:Butoxamine; D004082:Dihydroalprenolol; D000070:Acebutolol; D011433:Propranolol; D008790:Metoprolol; D007545:Isoproterenol; D000420:Albuterol; D009638:Norepinephrine; D004837:Epinephrine