Biomedical subjects

R Refinetti

Publications and source records attributed to R Refinetti.

58 records · Page 4Linked to original sources

PubMed1986

Complementary nature of heat production and heat intake during behavioral thermoregulation in the rat.

Rats were trained to work for radiant heat in a cold environment in an apparatus that permitted the simultaneous measurement of metabolic heat production. Reductions in behavioral efficacy produced either by a decrease in reward duration or intensity or by an increase in response effort resulted in a reduction in behavioral heat intake, an increase in metabolic heat production, and no change in body temperature. Thus, autonomic and behavioral temperature regulation interact to produce a constant body temperature.

Animals↗

PubMedDate not supplied

Day-night difference in the preferred ambient temperature of human subjects.

To investigate the existence of a day-night difference in thermal preference, 32 college students (16 male, 16 female) were asked to indicate a threshold of discomfort in a climate-controlled environment. The experiment was performed at two distinct times of day that corresponded to the peaks and troughs of the subject's circadian rhythm of body temperature. Males, but not females, felt comfortable at a higher ambient temperature during the trough than during the peak of the body temperature rhythm. These data support the hypothesis (derived from animal studies) that behavioral thermoregulation opposes the circadian rhythm of body temperature.

Adult↗

PubMedDate not supplied

Dark adaptation in the circadian system of the mouse.

Entrainment of circadian rhythms by zeitgebers is generally believed to conform to the principles of the so-called nonparametric theory of entrainment. Although seldom recognized, this theory presupposes that the response of the circadian system to photic stimulation is dependent on previous photic stimulation. The process of dark adaptation in the circadian system has been investigated previously in only two studies in golden hamsters. In this study, dark adaptation in the circadian system of the mouse was investigated through the measurement of phase shifts of the locomotor activity rhythm of animals maintained in constant darkness for varying intervals of time before receiving single light pulses. It was found that 3 weeks of darkness are necessary for attainment of full responsiveness to light, whereas even a single 1-h pulse is sufficient to suppress the responsiveness. Additional results of this study indicate that phase shifts of the locomotor activity rhythm are consistently associated with changes in free-running period in both mice and golden hamsters. Phase advances elicited by single light pulses are associated with a shortening of circadian period, whereas phase delays are associated with a lengthening of period. Each 1 h of phase shift is associated with a period change of approximately 3 min.

Animals↗

PubMedDate not supplied

Thermoregulation during pentobarbital and ketamine anesthesia in rats.

1.) Core temperature, tail temperature, metabolic heat production, and evaporative heat loss were measured in rats exposed to various ambient temperature conditions. 2.) Control rats increased heat production in the cold and heat loss in a warm environment, thus maintaining a relatively constant core temperature. 3.) Pentobarbital anesthesia reduced the thermoregulatory responses and caused core temperature to vary considerably with ambient temperature. Ketamine anesthesia resulted in minor thermoregulatory deficits. 4.) It is concluded that ketamine can be used in thermal physiological studies that require an anesthetised preparation, although it is not completely devoid of inhibitory effects on thermoregulatory responses.

Animals↗