Montelukast potentiates the relaxing effect of nifedipine in the porcine myometrium.

This study analysed the influence of montelukast (MON), a cysteinyl leukotriene receptor antagonist, and nifedipine, an L-type voltage-gated Ca2+ channel blocker, on the contractility of the porcine uterine smooth muscle. Myometrial strips were collected from the sexually immature (n=8), cyclic (12-14 days of the oestrous cycle; n=8) and pregnant (27-28 days of pregnancy; n=8) gilts and stimulated with a) MON or nifedipine at concentrations of 10-8-10-4 M and b) increasing concentrations of nifedipine after previous administration of MON at a concentration of 10-4 M. The changes in the tension, amplitude and frequency of contractions were determined with the Hugo Sachs Elektronik equipment for measuring isometric contractions. Stimulation of the uterine strips with high concentrations of MON significantly reduced the amplitude of contractions in both the cyclic and pregnant group and the frequency of contractions in the pregnant group. In high concentrations, nifedipine significantly decreased the amplitude and frequency of contractions in all examined groups. Nifedipine administered after MON pre-treatment significantly decreased the tension in the pregnant group and the amplitude and frequency of contractions in all examined groups; this effect was more evident in comparison with nifedipine used alone. The results obtained indicate that the influence of MON and nifedipine on the contractile activity of the porcine uterus is dependent on the physiological status of the animal. Moreover, the blockage of the CysLT1 receptor enhances the relaxing effect of nifedipine.