INTRODUCTION This study was designed to scientifically evaluate the effects of an aqueous extract of Muntingia calabura L. (M. calabura), a medicinal herb, on isoproterenol-induced myocardial infarction (MI) in rat models. METHODS Six groups of Wistar albino rats, each comprising six animals, were selected for this study. Group I served as a control, Group II rats were given isoproterenol (20...

Isoproterenol stimulates cellular accumulation of cyclic adenosine 3':5'-monophosphate (cyclic AMP) and produces a 2- to 4-fold increase in bidirectional potassium fluxes in turkey erythrocytes. Ouabain, which does not alter catecholamine-stimulated cellular cyclic AMP, inhibits potassium influx by 50 to 70%, does not alter potassium outflux or isoproterenol-stimulated potassium influx, but inc...

BACKGROUND Autoantibodies directed against the beta1-adrenergic receptor have been described in patients with dilated cardiomyopathy. These autoantibodies exert an agonistic, chronotropic effect on spontaneously beating cultured neonatal rat cardiomyocytes. We studied the effect of such antibodies on beta1-adrenergic receptor expression. METHODS AND RESULTS Cardiomyocytes were incubated with ...

Recent reports suggest that prostaglandins play an important role in the beta-adrenergic receptor mechanism of renin release. However, the site of the action of prostaglandins has not yet been clarified. Superfusion of rabbit renal cortical slices was used to evaluate the beta-adrenergic receptor mechanism of renin release. Renin release was stimulated by isoproterenol, prostaglandin E2, and di...

BACKGROUND We have previously shown major differences in beta-adrenergic and muscarinic modulation of L-type calcium currents (ICa) in newborn and adult rabbit heart. However, little is known about developmental changes in modulation of ICa by phosphodiesterases (PDEs), which also regulate intracellular cAMP concentration by its hydrolysis. METHODS AND RESULTS Enzymatically isolated adult and...

Isoproterenol produced an increase in pulmonary blood volume and pulmonary blood flow without a significant change in pulmonary vascular pressures in 14 patients with obstructive lung disease, six of whom had cor pulmonale. These findings are consistent with a vasodilating effect on the pulmonary vasculature. Evidence is presented that muscular pulmonary arteries constricted by hypoxia were aff...

Cultured fetal human retinal pigment epithelium (RPE) was grown on a permeable substrate and sealed in an Ussing chamber. The average electrical resistance (R) was 330 ohm-cm2, the average transepithelial voltage (Ve) was 3.0 mV (apical side positive), and the average short circuit current (Isc) was 9.1 microA/cm2. When these RPE preparations were exposed to isoproterenol (a beta-adrenergic ago...

men. Methods and Results. Responses to two 5-minute intravenous isoproterenol infusions (0.01 ug/kg/min and 0.02 pg/kg/min) were evaluated in six type A and six type B men after pretreatment with either dextrose placebo or atropine (1.2 mg). Atropine significantly potentiated T wave attenuation in the recovery period after isoproterenol infusion (0.30±0.07 mV) compared with placebo (0.54±0.09 m...

Background—Autoantibodies directed against the b1-adrenergic receptor have been described in patients with dilated cardiomyopathy. These autoantibodies exert an agonistic, chronotropic effect on spontaneously beating cultured neonatal rat cardiomyocytes. We studied the effect of such antibodies on b1-adrenergic receptor expression. Methods and Results—Cardiomyocytes were incubated with either t...

To establish a reliable isoproterenol induced heart dysfunction fetal rat model and understand the switches of contractile proteins, 45 pregnant rats were divided into 15 mg/kg-once, 15 mg/kg-twice, sham-operated once, sham-operated twice, and control groups. And 18 adult rats were divided into isoproterenol-treated and control groups. H&E staining, Masson staining, and transmission electron mi...