ISSN:
0095-9898
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Non-torpid P. californicus have body temperatures which increase slightly as ambient temperature increases from 5° to 35°C. Their minimum oxygen consumption fits Newton's law of cooling, since minimum thermal conductance below thermal neutrality is virtually constant at 0.19 ml O2 (gm hr °C)-1. There is a thermal neutral point at 32.5° rather than a thermal neutral zone. Oxygen consumption at the thermal neutral point is 0.97 ml O2 (gm hr)-1. Maximum thermal conductance, measured at 35°, is 0.37 ml O2 (gm hr °C)-1. Evaporative water loss accounts for 5 and 15% of the value of minimum and maximum thermal conductance, respectively.Minimum oxygen consumption of mice in torpor is continuously dependent on body temperature from thermal neutrality to deep torpor. Q10 values are between 1.6 and 3.2. The thermal conductance of torpid mice at ambient temperature below 30° is 0.19 ml O2 (gm hr °C)-1 which is identical to the minimum thermal conductance of non-torpid mice. Torpid mice at an ambient temperature of 30° have thermal conductance values between 0.23 and 0.40 ml O2 (gm hr °C)-1 depending on their posture.Maximum oxygen consumption is linearly related to body temperature. At a normal body temperature of 38°, it is 11.6 ml O2 (gm hr)-1 which is no greater than that of similar sized mammals which do not enter torpor.Although P. californicus consistently enters into and arouses from torpor at ambient temperatures of 15° to 30°, the torpor cycle is severely disturbed at temperatures between 10° and 12°. At these temperatures mice show irregular temporal patterns of torpor, do not enter torpor completely, and cannot arouse from torpor if body temperature falls below 15°.Observations on the behavior of torpid and non-torpid P. californicus at various ambient temperatures are included in this report.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1030650313
