Effect of calcium channel blockers on penile efection in rats / 대한비뇨기과학회지

ABSTRACT

Calcium channel blockers (CCBs) have a relaxatory effect on cardiovascular smooth muscles and newly developed Felodipine has more vascular selectivity than myocardiac effects. This study was undertaken to evaluate the effect of CCBs, including felodipine. on in-vivo penile erection and whether these drugs can be clinically applied to diagnosis and treatment of impotence in the future. We observed intracavernosal and systemic blood pressure changes to cavernous nerve stimulation (1Hz., 2-4V), intracavernosal injection of CCBs (felodipine, diltiazem, verapamil), calcium ionophore (A23187) and calcium channel promotor (Bay-K 8644) in Sprague-Dawley rats(weight 250-350 gm) using polygraph with the biopac data analyzing system. The results were as follows. 1) Injections administered in dose dependent manner of felodipine (10(-10) - 10(-6)M, n=8). diltiazem (10(-10) - 10(-6)M. n=8) and verapamil (10(-10) - 10(-6)M, n=8) caused increases in intracavernosal pressuret(CP) (p<0.05) with no significant difference observed among the three drugs. In most effective dose, a transient drop of systemic blood pressure was observed by a degree of 30% to 33% of preinjection values, although systemic blood pressure was spontaneously recovered in one minute. However, a longer plateau phase of maximal pressure and a longer duration of detumescence were observed with injection of felodipine (18 min., 20 min.) than with diltiazem (5min., 4min.) or verapamil (5min., 3min, p<0.05). In comparison with ECh of the three drugs, felodipine also showed the effects of 3.4 to 4.4 times larger than diltiazem or verapamil. 2) Intracavemous injections of Bay-K 8644 (10(-6) - 10(-4)M, n=18) or A23187 (10(-6) - 10(-4)M, n=18) in dose dependent manner were found to suppress the most effective dose of felodipine, diltiazem or verapamil-induced erection. These results suggest that penile erection is related to the movement of calcium through its channel and CCBs, especially felodipine, may be useful for the diagnosis and treatment of impotence in the future, although the clinical effect remains to be investigated.