-transparent.png){kind=logo}
The effects of the muscarinic cholinergic agonist methacholine on affinity of beta-adrenergic receptors for isoproterenol and on isoproterenol-induced stimulation of adenylate cyclase activity were assessed in canine myocardium. GTP and guanyl-5'-yl imidoiphosphate both decreased the affinity of beta-adrenergic receptors for isoproterenol without altering the affinity of these receptors for propranolol. Methacholine (10 nM to 10 micronM) antagonized the guanine nucleotide-induced reduction in beta-adrenergic receptor affinity for isoproterenol. This effect of methacholine was reversed by atropine. The choline ester had no effect on the affinity of beta-adrenergic receptors for isoproterenol in the absence of guanine nucleotides. Likewise, methacholine had no effect on the affinity of beta-adrenergic receptors for propranolol, either in the presence or absence of guanine nucleotides. Methacholine also attenuated GTP-induced activation of adenylate cyclase or isoproterenol-induced activation of the enzyme in the presence of GTP. The effects of methacholine on myocardial adenylate cyclase activity were apparent only in the presence of GTP. These effects were also reversed by atropine. The choline ester had no effect on adenylate cyclase activity in the presence of guanyl-5'-yl imidodiphosphate or NaF. The results of the present study suggest that muscarinic cholinergic agonists can regulate both beta-adrenergic receptors and adenylate cyclase by modulating the effects of GTP.
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
May 2002,
American journal of physiology. Regulatory, integrative and comparative physiology,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
August 1984,
The Journal of pharmacology and experimental therapeutics,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
January 1986,
Biochemical Society symposium,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
May 1989,
Biochemistry,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
November 1996,
Journal of cardiovascular electrophysiology,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
February 1994,
Nuclear medicine and biology,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
August 1999,
The Journal of pharmacology and experimental therapeutics,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
January 1988,
Advances in experimental medicine and biology,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
April 1990,
The Journal of biological chemistry,
A M Watanabe, and
M M McConnaughey, and
R A Strawbridge, and
J W Fleming, and
L R Jones, and
H R Besch
January 1984,
Journal of neuroscience research,
