Effects of salbutamol on intracellular calcium oscillations in porcine airway smooth muscle |
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Authors: | Prakash Y S; Van Der Heijden H FM; Kannan M S; Sieck G C |
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Abstract: | Prakash, Y. S., H. F. M. van der Heijden, M. S. Kannan, andG. C. Sieck. Effects of salbutamol on intracellular calcium oscillations in porcine airway smooth muscle. J. Appl.Physiol. 82(6): 1836-1843, 1997.Relaxation ofairway smooth muscle (ASM) by -adrenoceptor agonists involvesreduction of intracellular Ca2+concentration(Ca2+]i).In porcine ASM cells, acetylcholine inducesCa2+]ioscillations that display frequency modulation by agonist concentration and basalCa2+]i.We used real-time confocal microscopy to examine the effect ofsalbutamol (1 nM to 1 µM), a2-adrenoceptor agonist, onCa2+]ioscillations in freshly dissociated porcine ASM cells. Salbutamol decreased the frequency ofCa2+]ioscillations in a concentration-dependent fashion, completely inhibiting the oscillations at 1 µM. These effects were mimicked by acell-permeant analog of adenosine 3,5-cyclicmonophosphate. The inhibitory effect of salbutamol was partiallyreversed by BAY K 8644. Salbutamol reducedCa2+]ieven when sarcoplasmic reticulum (SR)Ca2+ reuptake andCa2+ influx were blocked.Lanthanum blockade of Ca2+ effluxattenuated the inhibitory effect of salbutamol onCa2+]i.TheCa2+]iresponse to caffeine was unaffected by salbutamol. On the basis ofthese results, we conclude that2-adrenoceptor agonists have little effect on SR Ca2+ releasein ASM cells but reduceCa2+]iby inhibiting Ca2+ influx throughvoltage-gated channels and by enhancingCa2+ efflux. |
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