| Abstract: | Prazosin has been used in the treatment of congestive heart failure. It is, however, not known whether prazosin gives only haemodynamic benefit or if it also produces a decrease in the cardiac sarcolemmal Na+-K+-ATPase which has been reported to be increased in the failing heart. The present investigation deals with the effect of 3 months of prazosin treatment in dogs with 3 months of induced mitral insufficiency (MI) on the sarcolemmal Na+-K+-ATPase activity. The dogs were divided into four groups each comprising of five dogs. A--normal; B--3 months of MI; C--6 months of MI; D--3 months of prazosin treatment after 3 months of MI. Three months of MI produced a decrease in the dp/dt and an increase in the end-diastolic pressure of left ventricle but no change in the index of left ventricular contractility and cardiac index. Also there was no change in the sarcolemmal Na+-K+-ATPase. There was a significant decrease in the index of left ventricular contractility and cardiac index and an increase in the LVEDP associated with a significant increase in the left ventricular sarcolemmal Na+-K+-ATPase at 6 months of MI. Sarcolemmal Mg2+-ATPase of both ventricles increased after 6 months of MI the significance of which is not known as yet. There was no change in the sarcolemmal Na+-K+-ATPase of the nonfailing right ventricle. Prazosin treatment prevented the deterioration of the left ventricular contractility and function and also prevented the increase in the sarcolemmal Na+-K+-ATPase observed in failing heart.(ABSTRACT TRUNCATED AT 250 WORDS) |
