Demonstration of kallikrein in a rat pancreatic acinar cell carcinoma.

Kallikrein was identified immunohistochemically and biochemically in a transplantable pancreatic acinar cell carcinoma of the rat. The concentration of immunoreactive kallikrein in tumor homogenates was the same as in the pancreas. Kallikrein in tumor cells exists as a proenzyme and is released into blood in high concentrations. The impact of the presence of a kallikrein-producing tumor on other kallikrein-containing organs and other possibly interrelated systems was investigated. The concentration of kallikrein in the submandibular gland and pancreas of host rats was not significantly different from that of control rats. Urinary kallikrein secretion was significantly increased, although this may be a result of the high plasma glandular kallikrein concentration combined with kidney damage. The plasma concentration of kininogen, kininase, and renin was not significantly different from control rats. Rats with tumor had significantly lower blood pressure than did control animals, and blood pressure was inversely related to the concentration of glandular kallikrein in plasma. However, it was not proven that the low blood pressure was due to the high concentration of kallikrein. Nephrectomized tumor rats gave a smaller hypotensive response to kininase inhibition than was expected from their high concentration of circulating kallikrein. This may be explained by the absence of the "free kallikrein" fraction in plasma of host rats.