Beta-adrenergic receptor activity of cerebral microvessels is reduced in aged rats.
The effect of age on beta- (beta) adrenergic receptor number (Bmax) and adenylate cyclase (AC) activity was determined in microvessels isolated from male F-344 rats at 3, 18, and 24 months of age. Scatchard analysis of [125I]iodocyanopindolol (ICYP) binding indicated reduced Bmax (fmol/mg) of microvessels isolated from 24 month old rats (27.2 +/- 4.9) compared with 3 month old (50.4 +/- 5.2) and 18 month old rats (p less than 0.01) (61.4 +/- 7.6). The basal AC activity (pmol cAMP/mg) in 24 month old rats (32.0 +/- 6.7) and in 18 month old rats (30.4 +/- 2.1) were significantly reduced compared to the basal activity in the young (50.1 +/- 4.2). The net isoproterenol or NaF stimulated AC activity in 24 month old rats (zero and 15.6 +/- 8.5 respectively) was also reduced compared to young rats (10.1 +/- 3.9 and 166.0 +/- 21.2 respectively). It is concluded that aging is associated with reduced isoproterenol stimulated AC activity of cerebral microvessels. This reduction is the product of reduced beta-adrenergic receptor number and reduced activity of AC in aged rat cerebral microvessels.
Tucson DVA Medical Center, University of Arizona College of Medicine.
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Mooradian
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Scarpace
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000375:Aging; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000254:growth & development* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008833:Microcirculation / Q000201:enzymology*; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D012044:Regression Analysis; D012969:Sodium Fluoride / Q000494:pharmacology; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D006160:Guanosine Triphosphate; D012969:Sodium Fluoride; D010869:Pindolol; D005723:gamma-Glutamyltransferase; D000469:Alkaline Phosphatase; D000262:Adenylyl Cyclases; D007545:Isoproterenol