Author:

Keywords:

Animals, Arteries, Calcium, Intracellular Membranes, Isoproterenol, Muscle, Smooth, Vascular, Rabbits, Science & Technology, Life Sciences & Biomedicine, Physiology, 0606 Physiology, 1106 Human Movement and Sports Sciences, 1116 Medical Physiology, 3101 Biochemistry and cell biology, 3109 Zoology, 3208 Medical physiology

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.