Biomedical subjects

K C Crisanti

Publications and source records attributed to K C Crisanti.

3 recordsLinked to original sources

PubMed2000

Age-dependent core temperature responses of conscious rabbits to acute hypoxemia.

Experiments were carried out on chronically instrumented newborn and older rabbits to characterize their core temperature (T(c)) responses to acute hypoxemia and to differentiate "forced" vs. "regulated" thermoregulatory responses. Three age ranges of kits were studied: 4-6, 9-11, and 28-30 days of age. During an experiment, T(c), selected ambient temperature (T(a)), and oxygen consumption were measured from kits studied in a thermocline during a control period of normoxemia, an experimental period of normoxemia or hypoxemia (fraction of inspired oxygen 0.10), and a recovery period of normoxemia. We reasoned that no change or a decrease in T(a) while T(c) decreased during hypoxemia would indicate a regulated thermoregulatory response, whereas an increase in T(a) while T(c) decreased during hypoxemia would indicate a forced thermoregulatory response. T(c) decreased during acute hypoxemia in the older kits but not in the 4- to 6-day-old kits; the decrease in T(c) was accentuated on postnatal days 28-30 compared with postnatal days 9-11. T(a) decreased or stayed the same during exposure to acute hypoxemia. Our data provide evidence that postnatal maturation influences the T(c) response of rabbits to acute hypoxemia and that the decrease in T(c) during hypoxemia in the older kits results from a regulated thermoregulatory response.

Acute Disease↗

PubMed1999

Aminophylline alters the core temperature response to acute hypoxemia in newborn and older guinea pigs.

In newborns and adults of a number of species, exposure to acute hypoxemia produces a "regulated" decrease in core temperature, the mechanism of which is unknown. The present experiments were carried out on chronically instrumented newborn (5-10 days of age; n = 27) and older (25-30 days of age; n = 23) guinea pigs to test the hypothesis that adenosine mediates this regulated decrease in core temperature. During an experiment, core temperature was measured by biotelemetry from animals studied in a thermocline during a control period of normoxemia, an experimental period of normoxemia or acute hypoxemia (fraction of inspired oxygen 0.10), and during a recovery period of normoxemia after an intraperitoneal injection of 10 mg/kg aminophylline (i.e., a nonspecific adenosine antagonist) or vehicle. Core temperature decreased significantly during hypoxemia after vehicle in both newborn and older guinea pigs. After aminophylline, however, newborn guinea pigs failed to significantly decrease their core temperature, whereas older guinea pigs exhibited an attenuated yet significant core temperature decrease during hypoxemia. Our data support the hypothesis that adenosine plays an age-dependent role in mediating the regulated decrease in core temperature that occurs in newborn and older guinea pigs during acute hypoxemia.

Adenosine↗

PubMed1998

Naloxone does not alter the "regulated" decrease in core temperature during hypoxemia in guinea pigs.

In newborns and adults of a number of species, exposure to acute hypoxemia produces a "regulated" decrease in core temperature, the mechanism of which is unknown. The present experiments were carried out in chronically instrumented newborn (5-10 days of age; n = 59) and older (25-30 days of age; n = 61) guinea pigs to test the hypothesis that the endogenous opioids mediate this regulated decrease in core temperature. During an experiment, core temperature, oxygen consumption, and selected ambient temperature were measured in a thermocline (linear temperature gradient of 10-40 degreesC) during a control period of normoxemia, an experimental period of normoxemia or hypoxemia (inspired oxygen fraction 0.10), and during a recovery period of normoxemia following an intraperitoneal injection of naloxone hydrochloride (a nonspecific opioid antagonist; 1, 2, or 4 mg/kg) or vehicle. Naloxone did not significantly alter basal core temperature or the core temperature response to acute hypoxemia in newborn or older guinea pigs. Naloxone did, however, decrease basal oxygen consumption in newborn and older guinea pigs and altered the thermoregulatory effector mechanism used to decrease core temperature during hypoxemia in the newborn guinea pigs. Our data do not support the hypothesis that the endogenous opioids mediate the regulated decrease in core temperature that occurs in newborn and older guinea pigs during exposure to acute hypoxemia.

Animals↗