THE RELEASE OF POSTERIOR PITUITARY HORMONE IN THE RAT BY NICOTINE AND LOBELINE

¹ Food and Drug Laboratory, Department of National Health and Welfare, Ottawa, Canada

Both lobeline and nicotine have been shown to release posterior pituitary hormone (vasopressin). Lobeline is nuich weaker than nicotine in this respect.

The effect of posterior pituitary hormone on the coronary flow was studied. A considerable reduction in the coronary flow was observed by doses of the posterior pituitary that can be released by the gland following lobehine and nicotine injection.

Both the drugs have an antidiuretic effect. Lobeline is 1/4 to 1/9 as potent tts nicotine in its antidiuretic effect in the rat. Lobeline also causes inhibition of water diuresis in man.

Lobeline and small doses of nicotine produce a fall of blood pressure in the rat and this vaso-depressor effect can be greatly reduced by atropine. Large doses of nicotine have vaso-pressor effect in this species which can be blocked by phenoxybenzamine.