SALIVARY GLAND SECRETORY MECHANISMS DURING NORMAL AND ALTERED FUNCTIONAL STATES

口腔的健康是由唾液分泌物维持的。的 唾液腺的主要功能是产生这些复杂的液体。 我们利用体外分散的细胞和培养的上皮细胞， 唾液腺，了解控制唾液形成的机制。我们 这些研究集中在自主神经递质调节， 分泌事件和相关的信号传导机制。在此 报告所述期间，研究的主要重点是审查 GTP结合调节（G）蛋白在分泌刺激中的作用， 大鼠腮腺特别是，我们已经证明Ca 2+动员 由毒蕈碱受体激动剂卡巴胆碱引起的反应是 未受百日咳毒素治疗影响（即涉及百日咳 毒素不敏感的G蛋白）。我们观察到类似的卡巴胆碱敏感性， 和激动剂敏感的细胞内Ca 2+池的能力， 再填充细胞外Ca 2+，在控制和毒素处理的细胞。 类似地，在来自百日咳的细胞中，Ca 2+对AlF 4的反应不受影响。 毒素处理的大鼠。我们还表征了高亲和力的GT3 在富含GS的腮腺膜中的活性。β-肾上腺素能受体 激动剂异丙肾上腺素可增加此GT3活性（Vmax约50%; 对Km无影响）并刺激这些膜中cAMP的形成。腺苷酸 环化酶活性在异丙肾上腺素存在下显著增加， GTPYS。霍乱毒素处理膜减少异丙肾上腺素诱导的 高亲和力GTP酶活性，并增加GTP诱导的cAMP形成 （+/-异丙肾上腺素）。这些数据表明，激动剂诱导的 高亲和力的GT3活性参与了 大鼠腮腺腺泡细胞的β-肾上腺素能刺激反应。

The health of the oral cavity is maintained by salivary secretions. The principal function of salivary glands is to produce these complex fluids. We utilize in vitro dispersed cells, and cultured epithelial cells of salivary glands, to understand mechanisms controlling saliva formation. We have focused these studies on autonomic neurotransmitter regulation of secretory events and associated signalling mechanisms. During this reporting period the primary focus of study has been directed at examining the role of GTP-binding regulatory (G) proteins in secretory stimuli in the rat parotid gland. In particular, we have shown that the Ca2+ mobilization response elicited by the muscarinic receptor agonist carbachol is unaffected by treatment with pertussis toxin (i.e. involves a pertussis toxin-insensitive G protein). We observed comparable carbachol sensitivity, and the ability of the agonist-sensitive intracellular Ca2+ pool to be refilled by extracellular Ca2+, in control and toxin-treated cells. Similarly, Ca2+ responses to AlF4 were unaffected in cells from pertussis toxin-treated rats. We also have characterized the high affinity GTPase activity in Gs-enriched parotid membranes. The beta-adrenergic receptor agonist isoproterenol can increase this GTPase activity (Vmax, about 5O%; no effect on Km) and stimulate cAMP formation in these membranes. Adenylyl cyclase activity is increased markedly in the presence of isoproterenol and GTPYS. Cholera toxin treatment of membranes decreases isoproterenol-induced high affinity GTPase activity and increases cAMP formation induced by GTP (+/- isoproterenol). These data suggest the agonist-induced increase in high affinity GTPase activity is involved in the deactivation of beta-adrenergic stimulated responses of rat parotid acinar cells.