| RESEARCH PAPER
|Year : 1995 | Volume
| Issue : 2 | Page : 94-100
Differential effects of verapamil and nifedipine on isolated vas deferens of guinea pig to various agonists
JD Bhatt, KG Hemavathi
In izolated vas deferens of guinea pig, verapamil in low concentrations (2 x 10-7 M and 2 x 10-6 M) produced leftward shift of the concentration-response curves and enhancement of the maximal response to acetylcholine (ACh), while higher concentration (2 x 10-5M) produced significant rightward shift of the concentration response curve and depression of the maximal response. Lower concentration (2 x 10-7 M) of verapamil produced leftward shift of concentration res 10. D onse curves of norepinephrine (NE) and dopamine (DA) while higher concentration (2x10-5M) produced significant rightward shift of the concentration response curves and depression of the maximal responses. Verapamil (2 x 10-7 M, 2 x 1 0-6M and 2 x 1 O-5M) produced concentration dependent rightward shift of the concentration response curve and depression of the Faximal response to potassium chloride (KCI) Nifedipine (2 x 10-7 M, 2 x 10-6 M and 2 x 10-5 M) produced concentration dependent rightward shift of the concentration response curves and depression of the maximal response to NE, ACh, DA and KCI. Both verapamil and nifedipine produced concentration dependent inhibition of the electrical field stimulation-induced contractile responses in guinea pig isolated vas deferens preparation. It is suggested that the voltage-operated calcium channels are more sensitive to both the calcium channel blockers than the receptor-operated calcium channels. Nifedipine is more potent than verapamil in antagonising receptor-operated calcium channels.
J D Bhatt
Source of Support: None, Conflict of Interest: None