TXB2: cardiostimulant effect that involves beta-adrenoceptor and Na+ + K+-ATPase activity.
The biological properties of Thromboxane B2 (TXB2) on isolated rat heart were studied. Its actions were compared with U-46619 a Thromboxane A2 mimetic compound and with isoproterenol. TXB2 induced a concentration-dependent increase in contractility, that was non-competitively antagonized by propranolol. In addition TXB2 inhibited Na+ + K+-ATPase activity at the same concentrations that influenced the mechanical activity. Inhibition of beta-adrenoceptors efficiently blocked the inhibitory action of TXB2 upon Na+ + K+-ATPase-activity. Isoproterenol simulated the positive inotropic effect and the inhibitory action of TXB2 on Na+ + K+-ATPase-activity. In contrast, U-46619 did not alter the basal dF/dt, neither the enzyme activity. The foregoing results suggest that TXB2 resembles the biological effect of catecholamines-inducing stimulation of myocardial contractility and inhibition of Na+ + K+-ATPase activity.
Pascual
J
J
Cefaprin--Conicet, Buenos Aires, Argentina.
Sterin-Borda
L
L
Wald
M
M
Borda
E S
ES
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006325:Heart Atria / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013929:Thromboxane B2 / Q000494:pharmacology*
D011450:Prostaglandin Endoperoxides, Synthetic; D011943:Receptors, Adrenergic, beta; D013929:Thromboxane B2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000254:Sodium-Potassium-Exchanging ATPase; D007545:Isoproterenol