Beal A M
Faculty of Science, University of New South Wales, Sydney 2052, Australia.
Comp Biochem Physiol A Mol Integr Physiol. 2003 Jan;134(1):195-204. doi: 10.1016/s1095-6433(02)00249-0.
Intracarotid infusions of l-phenylephrine at 1.0 or 10 nmol kg(-1) min(-1) were accompanied by increases in salivary amylase activity, protein, potassium, magnesium and chloride relative to cholinergically-stimulated saliva. Intravenous infusions of phenylephrine at the same dose rates had a lesser effect on salivary composition particularly protein. Propranolol administered with phenylephrine via the carotid artery, at an antagonist/agonist ratio of 10:1, was much more effective in blocking the phenylephrine-induced changes in salivary composition than equimolar infusion of phentolamine with phenylephrine. It was concluded that alpha(1)-adrenoreceptors were not present in functionally significant numbers in the gland and that the effect of phenylephrine on the kangaroo parotid was mediated by beta-adrenoreceptors. As the phenylephrine dose rates in the kangaroos were comparable with those used to determine alpha-adrenergic responses of eutherian salivary glands and as phentolamine appeared to have minor beta-sympathomimetic activity, at least one subtype of beta-adrenoreceptors in macropods may not be identical to its eutherian counterpart.
相对于胆碱能刺激的唾液，以1.0或10 nmol kg⁻¹ min⁻¹的剂量颈内注射去氧肾上腺素会伴随着唾液淀粉酶活性、蛋白质、钾、镁和氯的增加。以相同剂量速率静脉注射去氧肾上腺素对唾液成分（尤其是蛋白质）的影响较小。以10:1的拮抗剂/激动剂比例通过颈动脉与去氧肾上腺素一起给药的普萘洛尔，在阻断去氧肾上腺素诱导的唾液成分变化方面比与去氧肾上腺素等摩尔输注的酚妥拉明更有效。得出的结论是，该腺体中不存在功能上显著数量的α₁-肾上腺素能受体，而去氧肾上腺素对袋鼠腮腺的作用是由β-肾上腺素能受体介导的。由于袋鼠中去氧肾上腺素的剂量速率与用于确定真兽类唾液腺α-肾上腺素能反应的剂量速率相当，并且由于酚妥拉明似乎具有轻微的β-拟交感神经活性，有袋类动物中至少一种β-肾上腺素能受体亚型可能与其真兽类对应物不同。
