Hypothalamic thermosensitivity in California quail (Lophortyx californicus)

1. Manipulations of hypothalamic temperature (Thy) in California quail produced no significant changes in metabolic rate (MR) from the non-manipulated state (Figs. 1 and 2; Table 1). 2. MR was significantly influenced by ambient temperature (Ta), with MR decreasing as Ta increased (Figs. 2 and 3, Table 1). 3. Vasomotor responses to manipulations of Thy were elicited during 41% of the response opportunities. Vasomotor responsiveness appeared to be most active at a Ta of 30°C due to a decrease in threshold Thy for vasodilation as Ta increased. At Ta's of 10°C and 20°C, the birds maintained a constant vasoconstriction during most experiments (Figs. 1, 4, 5; Table 2). 4. Results from this study indicate that hypothalamic thermosensitivity plays no significant role in thermoregulation in California quail other than being a possible defense against severe brain hyperthermia. The significance of these results is discussed with regard to the divergent evolution of mammalian and avian thermoregulatory systems. © 1977 Springer-Verlag.

Duke Scholars

Author Sidney M. Gospe Jr. Pediatrics, Neurology