A Major Sex Difference in Kallikrein-Like Activity in the Rat Anterior Pituitary*

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Abstract
Male and female rat pituitaries were compared for their ability to release kinins from kininogen at pH 8.5 (kininogenase activity) and cleave chromogenic peptide substrates for various proteases at pH 8.0. The female anterior pituitary contained over 18 times more kininogenase activity than the male anterior pituitary. The neurointermediate lobe did not exhibit a significant sex difference in kininogenase activity. The kininogenase of the female anterior pituitary was sensitive to inhibition by aprotinin, but was resistant to soybean trypsin inhibitor. Female anterior pituitary homogenates also cleaved chromogenic peptide substrates for kallikrein over 15 times faster than male anterior pituitary homogenates. The results indicate a major sex difference in kallikrein-like activity in the rat anterior pituitary.