Treatment with verapamil reduces blood pressure and tends to normalize vascular responsiveness and ion transport in the spontaneously hypertensive rat.

Spontaneously hypertensive rats (n = 7) were treated with verapamil in the drinking water (0.9 g/L) for a 5-month period. Blood pressure and heart weight in these animals were significantly lower than in a control group of rats (n = 7) receiving tap water. Aortic preparations from spontaneously hypertensive rats treated with verapamil showed less dependency on extracellular calcium in isometric tension studies than did aortae from control rats. Net uptake of 22Na and 45Ca in the presence of ouabain was significantly lower in verapamil-treated aortae than in aortae from control spontaneously hypertensive rats. The results indicate that treatment with verapamil is an effective antihypertensive regimen in spontaneously hypertensive rats and furthermore may tend to normalize vascular responsiveness and ion transport.