THE RELATION OF ENDOGENOUS MELANOPHORE-EXPANDING HORMONE TO HYPERGLYCAEMIA IN XENOPUS LAEVIS

Abstract

SUMMARY 1. Xenopus laevis responds to injected adrenaline by an increase in the level of blood sugar. This increased blood sugar is apparently derived from liver and not from muscle glycogen. 2. Blood-sugar levels of Xenopus equilibrated on a black background (BB) and on a white background (WB) are statistically different throughout 6 months' starvation (P<0·05). On prolonged starvation for 14–16 months the lower blood-sugar level recorded in WB animals is not statistically different from that in BB animals (P> 0·10). 3. Xenopus shows a marked excitation hyperglycaemia, which is thought to be due to secretion of endogenous adrenaline. This hyperglycaemia is greatest in animals kept on a white background. 4. Xenopus equilibrated on black and white backgrounds show different hyperglycaemic responses to similar doses of adrenaline (P < 0·01). Compared with their own 'control-distilled water injection' levels, WB animals show an increase of blood sugar 40% higher than BB animals. 5. If melanophore-expanding hormone ('B') is an effective agent in decreasing the hyperglycaemic response to adrenaline, the greater effective level of circulating hormone in BB animals, together with their relatively reduced glycaemic response, supports the view that endogenous 'B' hormone plays a role in normal carbohydrate metabolism.