Blood glucose in crayfish—III. The source of glucose and role of the eyestalk factor in hyperglycemia of Cambarus robustus

Abstract

1. 1. The presence of a hormone in the eyestalks of Cambarus robustus which brings about hyperglycemia was confirmed. Immersion in boiling water for 5 min destroyed activity of the hormone. 2. 2. Isolated muscle treated with an eyestalk preparation released 0·130 mg glucose/100 mg dry weight more than untreated muscle. The difference was shown to be significant by the t- test . No such consistent difference was found with isolated digestive gland tissue. It was concluded that muscle is the principal contributor of glucose to hyperglycemia. 3. 3. Glucose (10 mg/100 ml) in the incubation medium significantly depressed the release of glucose from isolated muscle. 4. 4. Sodium fluoride mimics the effect of the hormone; 0·02 M concentration produced the maximal effect. 5. 5. The effects of the hormone and 0·1 M NaF were additive. 6. 6. These observations support the view that the eyestalk hormone acts on the muscle phosphorylase system and not in the regulation of blood glucose levels per se. The exact mode of action of the hormone is not known. 7. 7. Deprivation of oxygen caused marked hyperglycemia but no discernible accumulation of lactic acid.