POTASSIUM-DEFICIENCY IN RATS - EFFECTS ON RATES OF DEHYDRATION AND ELECTROLYTE HOMEOSTASIS

1. Three groups of rats were fed a nutritionally complete (C), potassi um-deficient (-K), or potassium-supplemented (+K) diet for 28 days fol lowed by passive exposure to a moderate heat stress (T-amb = 31.5 degr ees C) until a hypohydration level of 8-9% of initial body weight was achieved. 2. Significant (P < 0.05) hypokalemia was achieved in the -K group and, while final T-re was also increased (P < 0.05 vs C) in thi s group, time to achieve hypohydration and water loss during heat stre ss were unaffected. 3. Potassium (K+) levels were decreased and sodium (Na+) concentrations were increased in selected striated muscles of b oth the +K and -K groups (vs C), but electrolytes in critical tissues (heart, brain, kidney, liver) were unaffected by dietary intake. 4. Th e moderate hyperthermia achieved during the dehydration interval elici ted minor effects on several indices of heat stress/injury.