Cardiohepatic and gross pathological changes in rhesus monkeys after intravenous injection of purified cholera enterotoxin

Abstract

Preliminary experiments have been conducted to determine the lethal dose, survival time and cardiohepatic responses to a single i.v. injection of purified cholera enterotoxin in rhesus monkeys. Within 15 min after enterotoxin injection (50 μg/kg), systolic, diastolic and mean blood pressures showed transient increases, followed by sustained decreases throughout the experimental period. The indices of cardiac contractility increased initially and then declined. During an 8-hr period of observation, heart rate, cardiac output and stroke volume increased and liver functions and total peripheral resistance decreased. The survival time ranged from 12·5 to 18 hr in the toxin-inoculated monkeys. Diffuse hemorrhages throughout the body, especially in the cardiac muscle were observed at necropsy. Similar pathologic changes and death were also observed in pigtail and cynomolgus monkeys following an i.v. injection of cholera enterotoxin at the same dose. African green and capuchin monkeys were resistant to i.v. cholera enterotoxin challenge; no clinical illness was shown after a high dose (200 μg/kg) of cholera enterotoxin injection.