scholarly journals Inotropic effect of cyclic AMP in calf ventricular muscle studied by a cut end method.

1976 ◽  
Vol 260 (1) ◽  
pp. 117-141 ◽  
Author(s):  
R W Tsien ◽  
R Weingart
Keyword(s):  
Cyclic Amp ◽  
Inotropic Effect ◽  
Ventricular Muscle

Blockade of Cardiac Histamine Receptors by Promethazine

1974 ◽  
Vol 52 (1) ◽  
pp. 23-27 ◽  
Author(s):  
John H. McNeill ◽  
Subhash C. Verma
Keyword(s):  
Cyclic Amp ◽  
Guinea Pig ◽  
Histamine Receptors ◽  
Inotropic Effect ◽  
Guinea Pig Heart ◽  
Chronotropic Effects ◽  
Non Equilibrium

The inotropic and chronotropic effects of histamine on the isolated perfused guinea pig heart were antagonized by promethazine over a concentration range 4 × 10−6 – 16 × 10−6 M. Promethazine (4 × 10−6 M) decreased the ability of histamine (1 μg) to elevate cardiac cyclic AMP. A higher dose of histamine could not overcome the promethazine blockade. Promethazine (4 × 10− 6 M) did not block the inotropic effect of noradrenaline. Higher concentrations of promethazine, particularly 16 × 10−6 M did decrease the noradrenaline response. The data indicate that promethazine can interact with cardiac histamine receptors but the interaction is either noncompetitive or competitive non-equilibrium in nature.

Cyclic AMP and the positive inotropic effect of norepinephrine and phenylephrine

1977 ◽  
Vol 55 (2) ◽  
pp. 279-287 ◽  
Author(s):  
T. T. Martinez ◽  
J. H. McNeill
Keyword(s):  
Cyclic Amp ◽  
Cell Membrane ◽  
Time Course ◽  
Positive Inotropic Effect ◽  
Contractile Response ◽  
Contractile Force ◽  
Time Response ◽  
Inotropic Effect ◽  
Chronotropic Response ◽  
Right Atria

Time-response studies of the effects of norepinephrine and phenylephrine revealed that both agonists caused an increase in cyclic AMP levels before increases in contractile force in either the electrically stimulated left atria or spontaneously beating right atria of the rat. Norepinephrine caused a nearly sixfold increase in cyclic AMP, whereas phenylephrine produced only a 50% increase in the nucleotide. Pretreatment with reserpine did not affect the norepinephrine cyclic AMP response; however, the phenylephrine cyclic AMP response was abolished. Reserpine pretreatment did not significantly affect the contractile responses of either amine. In the presence of propranolol, norepinephrine was found to have the ability to produce an increase in contractile force in which cyclic AMP was apparently not involved. The time course of the contractile response induced by adrenergic amines was found to be remarkably influenced by the chronotropic response in spontaneously beating preparations while the cyclic AMP response was not greatly affected. This difference in the contractile response may be due to the ability of the chronotropic response to influence the flux of calcium through the cell membrane.

Sign in / Sign up

Export Citation Format

Share Document