REGULATION OF CALCIUM CHANNELS IN HEART CELLS

正常的心脏功能依赖于对肌浆的精确控制 钙浓度 电压调节钙通道是一种 这是控制机制的重要组成部分。 心脏病，如 肥厚型心肌病，其特征在于过度 细胞内Ca++积累，可能反映了一个原发性疾病， 钙通道功能，细胞内加工机制，或钙 信道合成或降级速率。 这些异常可能是 表示为通道内通道数量和分布的变化 细胞膜，或作为一个特定的通道故障。 为了验证这一 假设，钙通道的功能特性，在两个正常 和心肌病细胞进行比较。 合成和降解 钙通道的速率及其细胞内的某些方面 处理将在正常和心肌病心脏检查 细胞 细胞也将暴露于已知会影响钙的药物中 通道功能（β-肾上腺素能激动剂，Ca++通道阻滞剂）和 这些药物对通道合成和降解速率的影响， 将确定小区上信道的数量和分布。 所有 参数将作为培养时间的函数进行测量。 正常和心肌病（叙利亚仓鼠BIO 14.6）心脏细胞将被 培养学习。 将识别和定量钙通道 使用放射性配体[3 H]尼群地平。 的亲和力和数量 结合位点将通过过滤结合测定来确定。 的 钙通道（[3 H]尼群地平结合位点）在 细胞表面将通过光显微镜放射自显影法测定， 氚敏感胶片 通道的功能特性将是 通过测量45 Ca ++流入细胞的速率来表征 在K+诱导的去极化过程中， 膜片钳技术 钙的合成和降解速率 通道将由密度偏移法确定， 由Devreotes等人用于测量乙酰胆碱受体转换 rates. 糖基化在细胞内加工过程中的作用将是 使用衣霉素（tunicamycin），一种蛋白质糖基化的抑制剂进行检测。 的 心血管药物和其他几种手法对 将研究钙通道的数量和周转， 确定这些治疗是否会上调或下调。

Normal cardiac function depends on the precise control of myoplasmic calcium concentration. The voltage-regulated calcium channel is an important part of this control mechanism. Cardiac disease such as hypertrophic cardiomyopathy, which is characterized by excessive intracellular Ca++ accumulation, may reflect a primary disorder in either calcium channel function, intracellular processing mechanisms, or calcium channel synthesis or degradation rates. These abnormalities may be expressed as changes in the number and distribution of channels within the cell membrane, or as a specific channel malfunction. To test this hypothesis, the functional properties of calcium channels in both normal and cardiomyopathic cells will be compared. Synthesis and degradation rates of the calcium channel and some aspects of its intracellular processing will be examined in both normal and cardiomyopathic cardiac cells. Cells will also be exposed to drugs known to influence calcium channel function (Beta-adrenergic agonists, Ca++ channel blockers) and the effects of these drugs on channel synthesis and degradation rates, and the number and distribution of channels on the cell will be determined. All parameters will be measured as a function of time in culture. Normal and cardiomyopathic (Syrian hamster BIO 14.6) heart cells will be cultured for study. Calcium channels will be identified and quantitated using the radioligand, [3H]nitrendipine. The affinity and number of binding sites will be determined by a filtration binding assay. The distribution of calcium channels ([3H]nitrendipine binding sites) on the cell surface will be determined by light microscopic autoradiography using tritium sensitive film. The functional properties of the channels will be characterized by measurement of the rate of 45Ca++ flux into the cells during K+ induced depolarization and by single channel recording using the patch clamp technique. The rates of synthesis and degradation of calcium channels will be determined by the density shift method which was developed by Devreotes et al. for measurement of acetylcholine receptor turnover rates. The role of glycosylation in intracellular processing will be examined using tunicamycin, an inhibitor of to protein glycosylation. The effects of cardiovascular drugs and several other manipulations on the number and turnover of calcium channels will be studied in order to determine if up- or down-regulation occurs with these treatments.