BACKGROUND It has been proposed that metformin exerts protective effects on ischemic hearts. In the present study, we evaluated the effects of metformin on cardiac function, hemodynamic parameters, and histopathological changes in isoproterenol-induced myocardial infarction (MI). METHODS Male Wistar rats were divided into six groups (n = 6) of control, isoproterenol (100 mg/kg; MI), metformin...

We investigated whether M(2) muscarinic receptor activation opposes isoproterenol-induced relaxation in mouse urinary bladder and whether endogenous acetylcholine acts through a similar M(2) mechanism. When measured in urinary bladder from M(3) receptor knockout mice, the muscarinic agonist oxotremorine-M elicited only very weak contractions. In the presence of alpha,beta-methylene ATP (30 micr...

Several clinical trials have demonstrated that angiotensin-converting enzyme inhibitor (ACEI) and angiotensin II type 1 receptor blocker (ARB) are equally effective in the treatment of chronic heart failure. However, this has not been confirmed for acute cardiac dysfunction. We examined whether ACEI or ARB prevents isoproterenol-induced acute left ventricular (LV) dysfunction in dogs. LV dysfun...

The inotropic actions of isoproterenol in cat papillary muscles or trabeculae bathed in a salt solution containing 4 mM KCl were compared to those in similar muscles bathed in a salt solution containing 22 mM KCl. Although isoproterenol evoked the same increase in force of contraction in both groups of muscles, the time course of contraction differed markedly. In muscles bathed in 4 mM KCl, iso...

In the present study, the effects of cooling (to 28°C) on the vasodilatation induced by diazoxide (10(-9)-3×10(-4) M), isoproterenol (10(-9)-3×10(-4) M) and magnesium sulphate (0.1-30 mM) on serotonin-pre-contracted human umbilical artery and the role of nitric oxide in these effects were analyzed. Diazoxide, isoproterenol and magnesium produced concentration-dependent relaxation of human umbil...

The bronchodilator and cardiovascular activity of isoproterenol hydrochloride (Isuprel) 5.0 mg, Salbutamol 5.0 and 2.5 mg and saline administered by IPPB to 30 patients with chronic bronchial asthma were determined and compared. Equal doses of isoproterenol and Salbutamol had similar peak bronchodilator effect, but the peak effect was reached much earlier with isoproterenoL Salbutamol bad longe...

Isoproterenol, norepinephrine, and epinephrine covalently bound to glass beads exert a positive inotropic effect on isometrically contracting papillary muscles from cats. Immobilized isoproterenol maintains increases in force and velocity of contraction for more than 5 hr. 1 muM Cocaine potentiates the action of immobilized norepinephrine, isoproterenol, and epinephrine, but not of isoprotereno...

RATIONALE β-Adrenoceptor activation contributes to sudden death risk in heart failure. Chronic β-adrenergic stimulation, as occurs in patients with heart failure, causes potentially arrhythmogenic reductions in slow delayed-rectifier K(+) current (IKs). OBJECTIVE To assess the molecular mechanisms of IKs downregulation caused by chronic β-adrenergic activation, particularly the role of exchan...

In dispersed rat parotid gland acinar cells, the beta-adrenergic agonist (-)-isoproterenol, but not its stereoisomer (+)-isoproterenol, induced a transient 1.6-fold (at maximum stimulation, 2 x 10(-4) M) increase in cytosolic free calcium ([Ca2+]i) within 9 s, which returned to resting levels (approximately 190 nM) by 60 s. This [Ca2+]i response was not altered by chelating extracellular Ca2+ w...