Bile flow response to repetitive heat stress in rats.

BACKGROUND & OBJECTIVES: Heat stress produces loss of absorptive surface area of the small intestine, including the ileum which is the site of bile acid absorption. This may cause diarrhoea on account of the possible bile acid malabsorption. To explore this possibility, the effect of high ambient temperature exposure on bile flow was studied in the warm acclimated albino rats.

METHODS

Following heat exposure at 38 +/- 0.5 degrees C for 4 h/day, for up to 5 consecutive days, bile flow in the rats was measured gravimetrically under pentobarbital-induced anaesthesia, at steady rectal temperature (37 +/- 0.7 degrees C), and flow characteristics and rate were studied.

RESULTS

The bile flow increased with the rise in rectal temperature (Tre) in an anaesthetized animal but, the relationship between the two was not linear; the flow nearly ceased if rectal temperature exceeded 43 degrees-44 degrees C. At steady, near normal, rectal temperature, bile flow showed fluctuations and, repetitive heat exposure led to a significant increase in bile flow.

INTERPRETATION & CONCLUSION: Exposure to high ambient temperature modulates liver secretory function to enhance bile flow rate and increase bile acid absorptive load on the small intestine, whose absorptive function is known to be adversely affected in heat stress.