ALPHA-ADRENOCEPTOR SUBTYPE & CL CURRENT IN PAROTID ACINI

唾液的功能重要性在口干症患者中是明显的，缺乏唾液会导致舌头和粘膜疼痛；味觉和发音问题、吞咽、咀嚼、蛀牙和牙齿脱落；并且增加了口腔微生物过度生长的风险。唾液分泌的生理调节是由供给腮腺的神经释放去甲肾上腺素引起的，去甲肾上腺素随后激活腮腺腺泡细胞上的α -1肾上腺素受体（α -1 - ar），引起液体和电解质分泌。α 1- ar介导的液体分泌是由受体激活的Ca2+依赖性Cl-通道打开引起的。α 1- ar亚型引起Ca2+依赖性Cl-通道的激活和液体分泌尚不清楚。本研究将确定激活大鼠腮腺新鲜分离的单细胞中Ca2+依赖性Cl-通道的α - 1- ar亚型。全细胞Ca2+依赖性Cl-电流的Alpha1-AR激活将使用膜片钳技术的穿孔贴片配置进行测量。在存在和不存在5-甲基脲地尔、ws -4101和吡嗪的情况下，α 1- ar激活全细胞Ca2+依赖的Cl-电流将被用来确定α 1- ar亚型与Cl-外排和液体分泌的耦合。这些药物是竞争性拮抗剂，可用于区分已知存在于腮腺腺泡细胞上的α 1- ar亚型。将测量羟甲基唑啉、cirazoline和木甲基唑啉在刺激α - 1- ar诱导的全细胞Ca2+依赖性Cl-电流激活中的作用。这些咪唑啉激动剂将用于获得不同程度受体激活Cl-电流所需的药物结构信息。α 1- ar是否调节Na+-K+泵活性将使用膜片钳技术来测量其净向外电流。调节Na+-K+泵活性的α 1- ar亚型也将被确定。本研究将增加我们对α - 1- ar在调节腮腺液体分泌中的生理作用的认识，并可为选择性治疗口干症的药物设计提供合理依据。

The functional importance of saliva is apparent in patients with xerostomia where lack of saliva results in painful tongue and mucosa; problems with taste and phonation, swallowing, chewing, tooth decay and loss; and increased risk of microbial overgrowth in the oral cavity. Physiologic regulation of salivation results from release of norepinephrine from nerves supplying the parotid gland, which subsequently activates alpha-1 adrenoceptors (alpha1-AR) on parotid acinar cells causing fluid and electrolyte secretion. Alpha1-AR mediated fluid secretion results from the opening of receptor activated Ca2+-dependent Cl- channels. The alpha1-AR subtype causing activation of Ca2+-dependent Cl- channels and fluid secretion is unknown. This study will determine the alpha1-AR subtype that activates Ca2+-dependent Cl- channels in freshly dissociated single cells from rat parotid glands. Alpha1-AR activation of whole-cell Ca2+-dependent Cl- currents will be measured using the perforated-patch configuration of the patch-clamp technique. Alpha1-AR activation of whole-cell Ca2+-dependent Cl- currents in the presence and absence of 5-methylurapidil, WB-4101, and prazosin will be used to determine the alpha1-AR subtype coupled to Cl- efflux and fluid secretion. These drugs are competitive antagonists which are useful in distinguishing the alpha1-AR subtypes known to be present on parotid acinar cells. The effects of oxymetazoline, cirazoline, and xylometazoline in stimulating alpha1-AR induced activation of whole-cell Ca2+-dependent Cl- currents will be measured. These imidazoline agonists will be used to obtain information about the required drug structures needed for varying degrees of receptor-activated Cl- current. Whether or not alpha1-AR modulate Na+-K+ pump activity will be examined using the patch-clamp technique to measure its net outward current. The alpha1-AR subtype modulating Na+-K+ pump activity will also be determined. The present study will add to our understanding of the physiological role of alpha1-AR in regulating fluid secretion in the parotid gland and may provide a rational basis for the design of drugs selective for treating xerostomia.