Intracellular distribution of cardiac beta-adrenoceptors in SHR and WKY.
To compare the intracellular distribution of beta-adrenoceptors in isolated myocytes of SHR with that of age-matched WKY and to examine changes in the distribution with aging, we measured the number of cell surface and total beta-adrenoceptors in 6-(young groups) and 37-week old (old groups) SHR and WKY. The number of surface beta-adrenoceptors was significantly lower in 6-week old SHR compared with that in age-matched WKY. But there was no difference in the number of total beta-adrenoceptors between the two groups. The number of surface beta-adrenoceptors in old groups was significantly reduced compared with that in the young groups, in both SHR and WKY. However, the number of total beta-adrenoceptors in the old groups did not show any difference from that in the young groups. Isoproterenol-stimulated c-AMP formation in 6-week old SHR was significantly lower than that of WKY of the same age. Isoproterenol-stimulated c-AMP formation in the old groups was significantly reduced than that of the young groups in both SHR and WKY. These results suggested that (1) there may be a difference in the intracellular distribution of cardiac beta-adrenoceptors between 6-week old SHR and WKY, (2) the intracellular distribution of cardiac beta-adrenoceptors may be changed with aging, and (3) intracellular distribution might be related to the difference in c-AMP formation to beta-agonist.
Matsumori
Y
Y
First Department of Internal Medicine, Hyogo College of Medicine, Japan.
Ohyanagi
M
M
Kawamoto
H
H
Shibata
R
R
Iwasaki
T
T
D000262:Adenylyl Cyclases / Q000378:metabolism; D000319:Adrenergic beta-Antagonists; D000375:Aging / Q000378:metabolism; D000818:Animals; D006321:Heart / Q000294:innervation*; D006973:Hypertension / Q000378:metabolism*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000652:urine; D011412:Propanolamines; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D000262:Adenylyl Cyclases; D007545:Isoproterenol; C033394:CGP 12177; D009638:Norepinephrine