THE PHARMACODYNAMICS OF THE DOMESTIC FOWL WITH RESPECT TO ERGONOVINE AND ERGOTAMINE

¹ Department of Pharmacology of the University of Chicago

1. The practicability of the chicken as a laboratory animal is reaffirmed.

2. The alkaloids ergonovine and ergotamine are about equally effective in their action upon the circulatory system of the chicken as judged by the magnitude of the blood-pressure response, but the effects of ergonovine are more transitory.

3. Much smaller doses of ergonovine are required to produce pressor responses in chickens than in cats or in other laboratory animals.

4. In doses of about 10-20 mg. ergonovine and ergotamine are effective in inhibiting but not reversing the blood-pressure response to epinephrine in the chicken.

5. After moderate doses of ergonovine and ergotamine electrocardiograms show only a slowing of the heart. With excessive doses minor changes in the T-wave are observed.

6. In experiments on the perfused hearts of the fowl, cat, and rabbit small amounts of ergonovine and ergotamine give a striking reduction in the coronary flow. Ergotamine is some ten times more potent than ergonovine in this respect and also more persistent.

7. The response of the oviduct to these alkaloids is irregular except in the case of the uterine portion, which is always stimulated by ergonovine. Epinephrine inhibits all segments.

8. Studies on the isolated chicken intestine show a reduction in tone from ergonovine and ergotamine, the former being more effective. The response to both substances decreases from duodenum to colon.

It is a pleasure to acknowledge the helpful guidance of Professor E. M. K. Geiling throughout this investigation. A portion of the expenses of this work has been met by a grant from the Biological Research Fund of the University of Chicago.