| Abstract: | Rats with dietary potassium (K) depletion have an altered breathing pattern compared to age matched control rats. The K depleted rats also have a decreased body weight gain, basal metabolic rate and body temperature. In this study, age matched controls are underfed (UFC) to match for body weight gain and metabolic rate and controls are exposed to different ambient temperatures to alter metabolism and body temperature. Compared to UFC rats with the same body weight and basal metabolic rate the K depleted rats breathe slower and with a larger tidal volume in the basal state and in response to hypercapnia and hypoxia. With heat stress body temperature is increased in K depleted rats as is metabolic rate. While frequency is increased it is still slower than in controls at the same ambient and body temperatures. We conclude that the low metabolic rate and body temperature of K depleted rats is not the cause of the altered breathing pattern. In addition, it is shown that the hypothermia of K depletion is present only at ambient temperatures below the thermoneutral zone and that is is apparently due to an inability of the K depleted rat to increase metabolic heat production with cold stress. |
