Ultradian glucocorticoid rhythms in monkeys and rats continue during stress.

Previously we showed that rhesus monkeys have ultradian cortisol rhythms with periods of about 90 min that persist during the infusion of large amounts of adrenocorticotropin. The experiments reported here showed that rats exhibit ultradian corticosterone rhythms with a similar period (median period 61 min). However, rat ultradian corticosterone rhythms were distorted by large slow trends that had to be removed before the rhythm could be adequately assessed.

An analysis of some sensitizing agents in the pathogenesis of stress-induced gastric erosive disease.

Prior surgical implantation of a venous catheter sensitized rats to cold-immobilization stress. Three of six catheterized females succumbed during the stress. The remaining rats fell into two groups in terms of their core temperature at the end of the stress period: Male uncatheterized rats had higher temperatures than rats in the other three groups.

Plasma cortisol and appetitively motivated arousal in monkeys.

A disagreement exists in the literature as to whether plasma glucocorticoids are a sensitive index of emotional arousal. In order to provide further data on this subject, arousal in adult male rhesus monkeys was produced by classical appetitive conditioning done once every 48 hr. Monkeys showed significantly more aroused behavior during CS+ sessions than during CS- sessions.

Effects of stellectomy on cardiac rhythm disturbances induced by ouabain in guinea pigs.

The purpose of this study was first to provide further data on the role of the sympathetic nervous system in the pathogenesis of ventricular arrhythmias produced by digitalis administration and also to ascertain whether the left or right stellate ganglia had diverse effects on arrhythmogenesis. To do this, we subjected alpha-chloralose-anesthesized guinea pigs to either right, left, bilateral or sham stellectomy and then infused ouabain until death under constant ECG monitoring. Only guinea pigs with right stellectomy showed a significant change (i.

Termination of ouabain-induced cardiac arrhythmias by anterior hypothalamic stimulation.

Digitalis-toxic ventricular arrhythmias were produced in cats by repeated injections of ouabain. These arrhythmias converted to normal sinus rhythm significantly faster in cats receiving anterior hypothalamic stimulation than in sham stimulated controls. This effect was uncorrelated with changes in sympathetic activity along the renal nerve.

Ultradian rhythms of gastric acidity.

Measurements of gastric pH and hydrogen ion concentration were made serially for six hours in five rhesus monkeys. Both pH and hydrogen ion concentration showed rapid fluctuations with periods approximating 90 minutes. These rhythms persisted in the face of continuous infusion with Pentagastrin, indicating that while gastrin release is sufficient to stimulate acid secretion, it is not the only mechanism of acid control.

Role of luminal acidity in the pathogenesis of stress-induced gastroduodenal disease.

Infusion of progressively more acidic fluids into the stomachs of rats stressed by immobilization had disparate effects on gastric erosive disease despite their producing a stepwise fall in venous pH. At the highest concentration infused, disease was exacerbated. However, at lower concentrations, disease was ameliorated.

Ultradian rhythms in cognitive functions and their relationship to visceral processes.

Visceral and behavioral data were repeatedly sampled over time in 7 men performing tests of eye-hand coordination and of recall. Spectrum analysis of behavioral data showed peaks in the ultradian range which for the group were significantly different from white noise. Relations between visceral and behavioral data were not striking.

Relations between visceral and behavioral function in men at bedrest.

Multiple physiological measurements as well as a self-assessment of arousal was made in eight men on the first, third, and fifth days of bedrest. On the third day, additional measurements of performance on memory and dexterity tasks were made. Univariate analysis did not reveal any physiological variable to either predict subsequent performance well or to co-vary acutely with it; however, self-rating scores did prove to be useful predictors of subsequent performance.

Stress-induced heart failure.

Stress produced heart failure in cardiomyopathic hamsters (CMHs) with subclinical heart disease. CMHs exhibited a variety of peripheral manifestations of heart failure including subcutaneous edema, fluid in the abdominal and thoracic cavities, and increased organ weight. In contrast, stress did not produce heart failure in healthy hamsters.

Roles of stress and adaptation in the elicitation of face-immersion bradycardia.

Thirteen young healthy human volunteers immersed their faces in warm or cold water on one day while breathing through a snorkel and on another day while breath holding. The magnitude of the elicited bradycardia was most prominently due to water temperature, with apnea playing a less important role. Perceived stress could affect the magnitude of the response, but it was less important than the other variables.

Stress, predisposition and the onset of serious disease: implications about psychosomatic etiology.

Based on the author's own work and a review of the literature, the hypothesis is made that potentially lethal disease does not usually occur in healthy animals or people but does so when covert or overt disease exists or when a predisposition for disease exists. The author supports this hypothesis in his assessment of the human literature on sudden death. Further support for the hypothesis is presented from 2 animal models being studied in his laboratory--stress-induced heart failure in the cardiomyopathic hamster and stress-induced sensitization of digitalis-toxic ventricular arrhythmias.

Effect of linoleic acid on digitalis cardiotoxicity.

Adult male guinea pigs were anesthetized, catheterized and i.v. infused with either saline and then ouabain or with linoleic acid salt and then ouabain.

Vertebral artery injection of ouabain does not hasten arrhythmogenesis.

Cats were infused with ouabain into either their vertebral artery or their femoral vein, and latencies to early and late ventricular arrhythmia and death were determined. No significant differences were found between the 2 groups. These data question the likelihood that the area postrema is, as has been recently proposed, the primary site of action for digitalis-induced cardiac arrhythmias.

Plasma glucose and insulin levels in monkeys anticipating feeding.

To see whether plasma glucose or insulin changed in anticipation of feeding, we provided seven rhesus monkeys with four-hour access to food every other day. Blood was sampled before and during a 30-minute signal which ended with food availability and before and during a 30-minute signal which was not closely and reliably linked with food availability. Plasma insulin showed no evidence of conditioning.

Ultradian rhythm of plasma norepinephrine in rats.

This study examined the possibility that laboratory rats exhibit ultradian plasma catecholamine rhythms. Four rats were prepared with chronic venous cannulas. After recovery, blood was sampled every 15 min for 8 h.

Cholinergic activation produces psychosomatic digitalis toxicity.

The purpose of this study was first to develop an animal model for stress-induced digitalis toxicity in such a way that physical and psychological factors might be kept separate. The other purpose was to begin an analysis of the mechanism of this psychosomatic effect. To do this, free-ranging guinea pigs were subjected to repeated sessions of signaled shock (Pavlovian fear conditioning) or to signal alone.

The role of shock predictability during aversive conditioning in producing psychosomatic digitalis toxicity.

Guinea pigs were subjected to Pavlovian fear conditioning (signaled shock) and then infused with a fast acting digitalis preparation on a day when all experimental stimuli except shock were delivered. A significant shortening in latency to the onset of life-threatening digitalis toxicity was found when comparisons were made to control pigs that had never been shocked. This effect was not found in other guinea pigs infused with ouabain after exposure to sessions of unsignaled shock.