Effect of intracerebroventricular injection of nicotine and acetylcholine on renal water and salt excretion in conscious goats.

In hydrated, conscious goats nicotine was administered into the 3rd ventricle and its effects on water and electrolyte excretion were studied. Acetylcholine (ACh.) in combination with eserine (Es.) was injected by the same route in goats pretreated with atropine. Nicotine as well as large doses of Ach + Es. induced an antidiuresis of the pituitary type. The responses to ACh. were dose-dependent. Intracerebroventricular (icv.) pretreatment with hexamethonium blocked the responses to both nicotine and ACh., whereas atropine and propranolol were ineffective. It appears likely that nicotine receptors are involved inthe ACh.-induced release of antidiuretic hormone. Phentolamine (icv.) completely blocked the effects of ACh. + Es. and partly those of nicotine, indicating that catecholamines might be involved to some extent.