Abstract

The present study compared the acute effects of verapamil, diltiazem, nicardipine, and enalaprilat on lumbar sympathetic nerve activity (LSNA) in spontaneously hypertensive rats (SHR). Recording electrodes were secured to the lumbar nerve of 9-wk old male SHR. Twenty-four hours later in conscious rats, LSNA was recorded during infusion of verapamil, diltiazem, verapamil, or diltiazem sufficient to lower MAP by 20 mmHg over a 30 min period. Nicardipine and enalaprilat increased heart rate while diltiazem and verapamil suppressed heart rate. Changes in LSNA during acute blood pressure reduction for the study medications were:

These results indicate that in spite of differential effects on heart rate, the different types of calcium channel blockers acutely increase sympathetic activity to a similar degree. (See Figure)
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