Meeting Abstract

73.3  Sunday, Jan. 6  Endurance Capacity of Mice Selectively Bred for High Voluntary Wheel Running MEEK, T.H.*; HANNON, R.M.; LONQUICH, B.; MARSIK, R.L.; WIJERATNE, R.S.; GARLAND, T.Jr.; Univ. of California, Riverside; Univ. of California, Riverside; Univ. of California, Riverside; Univ. of California, Riverside; Univ. of California, Riverside; Univ. of California, Riverside tmeek001@ucr.edu

Mice from 4 replicate lines selectively bred for high voluntary wheel running tally ~3 times more revolutions/day as compared with 4 unselected control lines (C). The selected lines (S) also have an elevated VO2max during forced treadmill exercise. Therefore, we hypothesized that the S lines have a greater endurance capacity. 100 mice from generation 49 (half male, half female) were given wheel access for 6 days in accordance with the regular selection protocol. Mice were then trained to run on a motorized treadmill at an incline of 25 degrees for 15 min/day over the following 3 days. Treadmill speed for each day was 10, 14 and 18 m/min, respectively. On each of the following 2 days mice were tested using an incremental speed test. The starting belt speed was 20 m/min and speed was increased 1.5 m/min every 2 min. An air gun and an electrical grid with a mild current were placed at the back of the treadmill to provide motivation. Mice were judged to be exhausted when they remained on the electrical grid for four seconds. The testing procedure was repeated the following day. Blood samples were taken immediately following the second test. Four days later, a resting blood sample was obtained and mice were dissected. Both lactate and glucose were measured in whole blood. Endurance was highly repeatable between days (r = 0.80) and the S lines had significantly higher endurance (1-tailed P < 0.01). Post-endurance glucose and lactate levels averaged ~56 mg/dl and 6.5 mM/l, respectively, and did not differ between S and C lines. Supported by NSF IOB-0543429 to T.G.