Atrial muscle isolated from guinea pigs subjected to Escherichia coli endotoxin shock was used to study the myocardial changes associated with this experimental disease state. Isometric contractile tension and its first derivative (dT/dt) consistently were depressed by about 45% in muscle from the shock group (P less than 0.001), but contraction time intervals of the shock tissues were not sign...

The electromechanical responses to isoprenaline and a high calcium medium on cardiac muscles from nonhibernating and hibernating chipmunks were studied in the presence and the absence of ryanodine. In nonhibernating animal preparations, isoprenaline (5 X 10(-8) M) caused a marked positive inotropic effect with an increase in the amplitude of the action potential plateau and augmented the slow a...

Pi, YeQing, and Jeffery W. Walker. Role of intracellular Ca21 and pH in positive inotropic response of cardiomyocytes to diacylglycerol. Am. J. Physiol. 275 (Heart Circ. Physiol. 44): H1473–H1481, 1998.—Diacylglycerol has been hypothesized to mediate the positive inotropic response of myocardium to the a-adrenergic agonists angiotensin II and endothelin. The mechanism of action of diacylglycero...

The cardiotonic activity of a new, noncatechol, nonglycoside agent, amrinone, was investigated in vitro and in anesthestized and unanesthetized dogs. Amrinone (3-100 microgram/ml) caused a dose-dependent increase in papillary muscle developed tension and df/dt without significant changes in duration of the contractile cycle or time-to-peak tension. Amrinone induced slight increases in right atr...

The right atrium isolated from the dog heart was perfused through the cannulated sinus node artery with heparinized arterial blood led from a support dog anesthesized with 30 mg/Kg of sodium pentobarbital. When adenosine was administered into the sinus node artery, negative chronotropic and inotropic effects were dose-relatedly induced. The threshold dose for inducing the negative ones was 0.3 ...

To investigate the effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy, we studied 14 patients at catheterization with a nonimaging scintillation probe before and after serial intravenous infusions of low-, medium-, and high-dose verapamil (total dose 0.17 to 0.72 mg/kg). Percent change in radionuclide stroke counts after verapam...

Left atrial strips and right ventricular papillary muscles of kittens and left atrial strips of guinea pigs, rabbits, dogs, and chickens were exposed to ouabain, acetylstrophanthidin, or digoxin at 37°C during rest or while contracting at frequencies from 0.06 to 60/min. Both the positive inotropic effect and increases in resting tension developed fully in all preparations exposed to the three ...

Left atrial strips and right ventricular papillary muscles of kittens and left atrial strips of guinea pigs, rabbits, dogs, and chickens were exposed to ouabain, acetylstrophanthidin, or digoxin at 37°C during rest or while contracting at frequencies from 0.06 to 60/min. Both the positive inotropic effect and increases in resting tension developed fully in all preparations exposed to the three ...

HEART FAILURE OCCURS IN 4.7 million persons living in the United States, and is the discharge diagnosis in approximately 3.5 million hospitalizations annually. Hospitalizations account for 60% of health care expenditures for heart failure. Despite its enormous human and economic burden, no new intravenous agents for acutely decompensated congestive heart fa i lure (CHF) have been approved for u...