J. Neumann et al., SODIUM-FLUORIDE ATTENUATES THE NEGATIVE INOTROPIC EFFECTS OF MUSCARINIC M(2) AND ADENOSINE RECEPTOR AGONISTS, European journal of pharmacology, 294(2-3), 1995, pp. 451-457
Sodium fluoride increased the force of contraction in isolated guinea-
pig papillary muscles concentration dependently, starting at 3 mmol/l.
Sodium fluoride inhibited phosphorylase phosphatase activity in homog
enates from guinea pig hearts, starting at 1 mmol/l. The positive inot
ropic effect of 3 mmol/l sodium fluoride was not accompanied by an inc
rease in cAMP content in guinea-pig papillary muscles. In papillary mu
scles, carbachol or (-)-N-6-phenylisopropyladenosine reduced the posit
ive inotropic effect of isoprenaline (10 nmol/l) or the phosphodiester
ase inhibitor 3-isobutyl-1-methylxanthine (60 mu mol/l). These negativ
e inotropic effects of carbachol and (-)-N-6-phenylisopropyladenosine
were attenuated by additional sodium fluoride (3 mmol/l). It is conclu
ded that sodium fluoride can impair the signal transduction of muscari
nic M(2) (carbachol) and adenosine receptor ((-)-N-6-phenylisopropylad
enosine) agonists. This effect of sodium fluoride could support the hy
pothesis that the cardiac effects of muscarinic M(2) and adenosine rec
eptor agonists involve, at least in part, the activation of phosphates
.