title: Effect of isoprenaline on intracellular Ca uptake and on Ca influx in arterial smooth muscle.
abstract: We have investigated the effect of isoprenaline on the amplitude of the transient contraction of isolated arteries induced by releasing the intracellular Ca with an agonist during incubation in a Ca-free solution. Under some conditions this force development is an indication of the amount of Ca in the intracellular store. Loading the store in high K+ solution in the presence of isoprenaline increases the amplitude of the subsequent contraction in Ca-free solution by 6 to 16% as compared to the control. The presence of isoprenaline during the loading procedure in the control solution with 5.9 mM K+ does not affect the amplitude of the subsequent contraction of the rabbit ear artery. In the rabbit coronary artery such pretreatment with isoprenaline inhibits the contraction to 40% of the control. These results indicate that beta-agonists may stimulate the Ca uptake in the intracellular store and, depending on the tissue, inhibit the influx of Ca.
mesh_terms: D000818:Animals; D001158:Arteries; D002118:Calcium / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011817:Rabbits
chemical_list: D007545:Isoproterenol; D002118:Calcium