Kallikrein-kinin and renin-angiotensin systems in rat renal lymph

Rat renal lymph contains 254 +/- 17 ng/ml (means +/- SEM, N = 20) of immunoreactive glandular kallikrein. Like the immunoreactive glandular kallikrein in plasma, it is biologically inactive. Gel filtration of renal lymph reveals profiles for immunoreactive glandular kallikrein, protein, and inhibition of trypsin and kallikrein which resemble those seen for plasma except that high molecular weight plasma components are reduced or missing in renal lymph. In contrast, gel filtration of thoracic lymph reveals immunoreactive glandular kallikrein and protein profiles which are indistinguishable from those seen with plasma. Renin levels are 170-fold higher in renal lymph than in thoracic lymph while angiotensin-converting enzyme levels are only 16% those of thoracic lymph. In keeping with the high renin and low converting enzyme activities, renal lymph contains high levels of angiotensin I. Immunoreactive glandular kallikrein levels in renal lymph, thoracic lymph and plasma do not show the striking differences observed for renin.