Development of vasomotor control in lean (+/?) and genetically obese (fa/fa) rat pups.
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 (Ta) alternating between thermoneutrality and cold loads resulting in a 50-100% increase of metabolic rate (MR) above its thermoneutral value, while core temperature (Tc), skin blood flux at the hindpaw, and MR were recorded. In all age groups, blood flux changed significantly in response to these Ta 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 Ta dependency of Tc 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 Ta with MR in the fa/fa pups, but no difference in the correlation of Ta 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.
Döring
H
H
Max-Planck-Institut für physiologische und klinische Forschung, W.G. Kerckhoff-Institut, Bad Nauheim, Germany.
Sann
H
H
Schmidt
I
I
D000818:Animals; D001481:Basal Metabolism / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D009765:Obesity / Q000235:genetics* / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D011914:Rats, Inbred BN; D011924:Rats, Zucker; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply; D014666:Vasomotor System / Q000254:growth & development* / Q000502:physiology