Development of vasomotor control in lean (+/?) and genetically obese (Fa/fa) rat pups

Author(s): Sann, H., Schmidt, I.

Journal/Book: Physiol Behav. 1999; 66: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 303-308.

Abstract: Using laser Doppler flowmetry, we determined whether vasomotor control is already functional in 7-, 11-, and 16-day-old rat pups, and whether differences in vasomotor responses between 16-day-old lean (+/?) and fatty (fa/fa) pups occur. For 3 h, at the end of their daily light phase, the pups were exposed to 30-min step changes of ambient temperature (T-a) alternating between thermoneutrality and cold loads resulting in a 50-100% increase of metabolic rate (MR) above its thermoneutral value, while core temperature (T-c) skin blood flux at the hindpaw, and MR were recorded. In all age groups, blood flux changed significantly in response to these T-a changes. The time needed for a significant change in blood flux was shorter in the 7-day-old than in the 16-day-old lean pups, while the T-a dependency of T-c was more pronounced in the younger pups. Comparison of the responses of the 16-day-old fatty and lean pups showed a parallel shift to lower values in the correlation of T-a with MR in the fa/fa pups, but no difference in the correlation of T-a with blood flux. This demonstrates that the vasomotor control system in the rat is already functional by the age of 7 days, and that the fa/fa lesion influences the vasomotor control less than the metabolic cold defense.

Note: Article Schmidt I, Max Planck Inst Physiol & Klin Forschung, WG Kerckhoff Inst, Parkstr 1, D-61231 Bad Nauheim, GERMANY

Keyword(s): thermoregulation; sympathetic system; laser Doppler flowmetry; CORE TEMPERATURE; IMMATURE RAT; ZUCKER RAT; THERMOREGULATION; RESPONSES; CYCLE; INNERVATION; MATURATION; RHYTHMS; DEFECT

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