Active sensitization discriminates between groups of calcium antagonists in lung parenchyma strips.

When considering the therapeutic potential of calcium antagonists in asthma, attention should be paid to the existence of marked differences among these compounds. In the present study, we have compared the effect of verapamil, diltiazem, nifedipine and trifluoperazine on contractions generated by different mechanisms (CaCl2 acting on K+ depolarized preparation, depolarization by KCl, receptor activation by acetylcholine) in lung parenchyma strips isolated from control and actively sensitized guinea-pigs. It was found that verapamil and diltiazem need higher concentrations in the sensitized specimens to elicit the same degree of inhibition obtained in controls. The reverse was found for trifluoperazine while nifedipine had an intermediate position. In conclusion, acute sensitization reveals differences between the various groups of calcium antagonists in their ability to influence agonist-induced lung parenchyma strip contraction, a finding that suggests that these drugs may also behave diversely in the clinical setting.