Hemodynamic and metabolic effects of chronic carbon monoxide exposure in cynomolgus monkeys (Macaca fascicularis).

Cardio-respiratory data were obtained on four adult female cynomolgus monkeys, intermittently exposed to CO for eight months and compared with data obtained from the same animals after five weeks of recovery. Due to CO exposure, the arteriovenous oxygen concentration difference and oxygen consumption decreased and blood oxygen affinity increased. However, there was no significant change in cardiac output and mixed venous PO2. The cynomolgus monkeys adapted to chronic CO exposure by reducing their metabolic rate.

Cardiovascular and respiratory responses to ketamine hydrochloride in the rhesus monkey (Macaca mulatta).

Catheters were placed in the left ventricle and pulmonary artery of 12 rhesus monkeys (Macaca mulatta). Heart rate, left ventricular systolic pressure, pulmonary arterial systolic and diastolic pressure, and respiratory rate were measured before and 5, 15, and 30 minutes after intramuscular injection of the monkeys with ketamine HCl (10 mg/kg). Heart rate, systolic pressure in the left ventricle, and respiratory rate decreased significantly. No significant changes occurred in the pulmonary arterial pressure.

Heart rate in caged Macaca fascicularis. Effects of short-term physical exercise.

Electrocardiograms were recorded hourly for five days in 16 caged Macaca fascicularis by means of a miniaturized ECG transmitter connected to two chest leads. The lowest heart rates were 135 +/- 35 (mean +/- SD, n= 31) beats/min at 5 a.m., and the highest were 192 +/- 22 (n = 29) beats/min at 3 p.m. Sinus arrhythmia was common. Eight of the animals were trained to exercise in a specially designed enclosed treadmill; their heart rates were recorded daily during two 10-min periods of running at 3.4 km/h. Transfer of the monkeys (n k0) to the treadmill increased heart rate from 186 +/- 24 to 228 +/- 23 beats/min; exercise further increased it to 271 +/- 8 beats/min.

Effects of bilateral amygdaloid lesions on gonadal and pituitary hormones in serum and on sexual behavior in female rhesus monkeys.

Bilateral lesions that destroyed the amygdaloid nuclear complex failed to alter either serum concentrations of luteinizing hormone (LH), estradiol (E2), progesterone, and testosterone or sexual behavior in female rhesus monkeys. In 3 of 5 females ovulation occurred in the postoperative cycle, and in 4 of 5 females exogenous E2 treatment released a surge of LH whose pattern was indistinguishable from the normal preovulatory surge. A postcastration rise in serum LH also occurred in the 5 lesioned monkeys, and E2 again induced an LH release. The data suggest that the amygdala does not play a major role in regulation of LH or ovarian steroid secretion during the menstrual cycle. Moreover amygdaloid lesions in female monkeys do not alter their sexual behavior.

The effect of diet on hepatic bile formation and bile acid metabolism in squirrel monkeys with and without cholesterol gallstones.

In order to explain why squirrel monkeys on some experimental diets develop cholesterol gallstones, we made a number of measurements on bile acid kinetics and on bile secretion and composition. The pool size of cholic acid was much greater in monkeys on a commercial diet than in any group on a semipurified diet. It was also greater in squirrel monkeys on a lithogenic diet but without gallstones than in monkeys from the same diet group with gallstones. The half-lives of cholic acid tended to be proportional to pool size, and absolute rates of cholic acid synthesis were, therefore, not much affected by diet. Diet did not affect the pool sizes and half-lives of chenodeoxycholic acid as much as those of cholic acid. Dietary cholesterol increased concentrations of cholesterol relative to bile acids and phospholipids in hepatic bile as well as absolute secretory rates of all three components. Interruption of the enterohepatic circulation of bile in fasted monkeys with gallstones resulted in a more rapid and marked increase in the relative cholesterol concentration and decline in the absolute concentration of bile acids in hepatic bile than occurred for monkeys without gallstones. This was due to the low proportion of the bile acid pool outside the gallbladder and the low rate of new bile acid synthesis of the monkeys with gallstones during fasting.

Failure of carbon monoxide to induce myocardial infarction in cholesterol-fed cynomolgus monkeys (Macaca fascicularis).

Twenty-six adult female cynomolgus monkeys (Macaca fascicularis) were randomly assigned to four groups which were fed on a standard laboratory diet or a semipurified diet containing cholesterol. In two of the groups, the monkeys were exposed intermittently to CO throughout the day for 14 months; the control animals breathed room air. No myocardial infarctions were observed, and the ECG showed a transitory injury current in only one animal. No differences in plasma cholesterol levels or in aortic and coronary atherosclerosis could be attributed to CO exposure.

Radiographic approach to stereotaxic surgery in rhesus monkeys.

A method is described which uses radiographic techniques to identify ventricular and bony landmarks as guides in placing probes into specific areas of the brain in the rhesus monkey. This approach requires a relatively simple modification of a standard stereotaxic instrument and is applicable to various physiological and behavioral experiments in species where cranial variability limits the accuracy of stereotaxic surgery.