Selectively breeding lines of mice and rats to differ in alcohol intake has proven useful for defining which traits correlate with high alcohol drinking behavior, as well as for creating animal models of alcoholism. This study reports the derivation of two novel sets of selected lines, High Alcohol Preferring (HAP) and Low Alcohol Preferring (LAP) replicate 2 and 3 lines. Mice were mass-selected using the same procedure as in the replicate 1 lines: using HS/Ibg as a progenitor, mice were selected for differences in 2-bottle choice intake of 10% alcohol during a 4-week testing period. In addition, another high drinking line, the crossed HAP (cHAP) line was selectively bred from a progenitors that were a cross of replicate 1 (S27) X replicate 2 (S21) HAP lines. All lines were characterized for saccharin intake. Overall, the response to selection of the HAP and LAP replicate 2 and 3 lines was quite similar. As anticipated, following selection, the cHAP line drank more than either parent HAP line (consuming 26.0 g/kg per day of alcohol by S11), suggesting that this method of crossing replicate lines and selecting from that cross captures more alleles than any single selected line, as well as producing a line with exceptionally high voluntary alcohol intake. As expected, saccharin consumption was highly associated with alcohol consumption; data from all 8 lines (HAP 1, 2, and 3, LAP 1, 2, and 3, HS/Ibg, and cHAP) indicated a genetic correlation between 10% alcohol and 0.32% saccharin intake of 0.917. Overall, these findings show the practicality of developing replicate lines divergent in alcohol preference, and validate a novel procedure for generating very high-drinking mouse populations.

Carbohydrate stores within muscle are considered essential as a fuel for prolonged endurance exercise, and regimes for enhancing such stores have proved successful in aiding performance. This study explored the effects of a hyperglycaemic-hyperinsulinemic clamp performed 18 h previously on subsequent prolonged endurance performance in cycling. Seven male subjects, accustomed to prolonged endurance cycling, performed 90 min of cycling at ~65% VO(2max) followed by a 16-km time trial 18 h after a 2-h hyperglycemic-hyperinsulinemic clamp (HCC). Hyperglycemia (10 mM) with insulin infused at 300 mU/m(2)/min over a 2-h period resulted in a total glucose uptake of 275 g (assessed by the area under the curve) of which glucose storage accounted for about 73% (i.e. 198 g). Patterns of substrate oxidation during 90-min exercise at 65% VO(2max) were not altered by HCC. Blood glucose and plasma insulin concentrations were higher during exercise after HCC compared with control (p < 0.05) while plasma NEFA was similar. Exercise performance was improved by 49 s and power output was 10-11% higher during the time trial (p < 0.05) after HCC. These data suggest that carbohydrate loading 18 h previously by means of a 2-h HCC improves cycling performance by 3.3% without any change in pattern of substrate oxidation.

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