ALPHA-ADRENOCEPTOR SUBTYPE & CL CURRENT IN PAROTID ACINI

α-肾上腺素能受体亚型

• 批准号: 2856667
• 负责人: CHARLES S BOCKMAN
• 金额: $ 1.51万
• 依托单位: CREIGHTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2856667
• 关键词: acinar cell; alpha adrenergic agent; alpha adrenergic receptor; calcium ion; chloride channels; imidazole; laboratory rat; norepinephrine; parotid gland; receptor coupling; receptor expression; secretion; single cell analysis; sodium potassium exchanging ATPase; voltage /patch clamp

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.

唾液的功能重要性对于口干症患者来说是显而易见的，因为缺乏唾液会导致舌头和粘膜疼痛；味觉和发声、吞咽、咀嚼、蛀牙和脱落问题；口腔微生物过度生长的风险增加。 流涎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，随后激活腮腺腺泡细胞上的α1肾上腺素受体（α1-AR），导致液体和电解质分泌。 Alpha1-AR 介导的液体分泌是受体激活的 Ca2+ 依赖性 Cl- 通道开放的结果。 导致 Ca2+ 依赖性 Cl- 通道激活和液体分泌的 α1-AR 亚型尚不清楚。 本研究将确定在大鼠腮腺新鲜分离的单细胞中激活 Ca2+ 依赖性 Cl- 通道的 α1-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膜片配置进行测量。 在存在或不存在 5-甲基乌拉地尔、WB-4101 和哌唑嗪的情况下，全细胞 Ca2+ 依赖性 Cl- 电流的 Alpha1-AR 激活将用于确定与 Cl- 流出和液体分泌相关的 α1-AR 亚型。 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 α1-AR 亚型。 将测量羟甲唑啉、西拉唑啉和赛洛唑啉在刺激 α1-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取不同程度的受体激活Cl-电流所需的药物结构的信息。 使用膜片钳技术测量其净外向电流来检查α1-AR是否调节Na+-K+泵活性。调节Na+-K+泵活性的α1-AR亚型也将被确定。 本研究将加深我们对α1-AR在调节腮腺液体分泌中的生理作用的理解，并可能为设计选择性治疗口干症的药物提供合理的基础。