The effect of anti-insulin serum and alloxan-diabetes on the distribution and multiple forms of hexokinase in lactating rat mammary gland.

1. The distribution and multiple forms of hexokinase activity in lactating rat mammary gland were investigated in alloxan-diabetic rats and in rats treated with anti-insulin serum. It was found that 46% of the total hexokinase of mammary-gland tissue from control rats was in the particulate fraction, but this percentage was decreased in the alloxan-diabetic rats to 11% of the total hexokinase. The hexokinase activity of the soluble fraction was not significantly altered but there was a decrease in the type II/type I quotient. 2. The early changes that occurred on insulin deprivation were studied 1hr. after administration of anti-insulin serum to lactating rats, at which time the hexokinase bound to the particulate fraction had decreased to 11% of the control value and that in the soluble fraction had increased by approx. 50%. The hexokinase type II/type I quotient in the soluble fraction was significantly decreased. These results suggested that there was a release of particulate-bound hexokinase in rats treated with anti-insulin serum.