SOME EFFECTS OF BULBOCAPNINE ON THE PERIPHERAL VASCULAR SYSTEM

¹ From the Departments of Physiology, School of Medicine, The George Washington University, Washington, D. C., and University of Chicago, Chicago, Illinois

1. Arterial and venous blood pressures were recorded on eleven dogs under ether anesthesia and 644 pressure curves were measured before and after the intraperitoneal injection of bulbocapnine.

2. Assay doses of adrenaline, mecholyl, pitressin and histamine were injected intravenously to determine any change in their vascular effectiveness in the presence of bulbocapnine.

3. Doses of bulbocapnine ranging from 3 to 60 mgm. per kilogram produced an average decrease of 37 per cent in the arterial and 50 per cent in the venous blood pressure within 30 minutes after the injection.

4. It is believed that bulbocapnine interferes with the peripheral vasomotor mechanism because adrenaline and mecholyl are less effective in altering arterial pressure after bulbocapnine than before, whereas the effectiveness of pitressin and histamine is increased or unchanged.

5. These venous pressure studies tend to exclude cardiac decompensation as a factor in the vascular picture of bulbocapnine catatonia.

6. Venous pressure tends to have a higher correlation with arterial pressure after the injection of bulbocapnine than before. This may be due to a decreased irritability of the peripheral vasomotor mechanism.

7. It is suggested that the static pulse of bulbocapnine catatonia is due to a decreased irritability of the vasomotor mechanism.

8. It seems probable that the peripheral vascular changes precede the muscular phenomena of bulbocapnine catatonia and that the vascular change is concomitant with the bulbocapnine narcosis.