title: Role of perfusate hydrogen ion activity in kallikrein release from isolated rat kidneys.
abstract: The present experiments were performed to investigate whether renal kallikrein release by isolated perfused rat kidneys correlates with acid-base-related parameters. Kallikrein excretion per millilitre of glomerular filtrate was inversely correlated with perfusate pH (r = -0.49, P < 0.001) and HCO3- concentration (r = -0.46, P < 0.005). A direct relationship between kallikrein excretion per millilitre of glomerular filtrate and urinary Na+/K+ ratio was found (r = 0.59, P < 0.001). Some 86% of the variability (F ratio 110, P < 0.00001) of urinary kallikrein activity was attributable to the perfusate pH and the urinary cation ratio. Therefore, urinary kallikrein activity was highly correlated with perfusate H+ activity corrected by the urinary Na+/K+ ratio (r = 0.92, P < 0.0001). Kallikrein secretion into the distal tubular fluid appears to be regulated by blood H+ activity, and modulated by factors that affect the distal Na+ and K+ handling. The HCO3 - excretion rate was inversely correlated with the urinary kallikrein activity (r = -0.62, P < 0.001). This finding confirms previous data from the author's laboratory showing a kallikrein involvement in the regulation of HCO3- secretion in rats and rabbits. Kallikrein probably transduces the sensing of interstitial fluid H+ activity by the connecting tubule cells into an appropriate translocation of HCO3- or H+ to the tubular lumen by the intercalated cells.
authors.affiliation: Physiologisches Institut, Ludwig-Maximilians-Universität zu München, Pettenkoferstrasse 12, D-80336 Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Marin-Grez
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D001639:Bicarbonates / Q000652:urine; D005919:Glomerular Filtration Rate; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007610:Kallikreins / Q000378:metabolism* / Q000652:urine; D007668:Kidney / Q000378:metabolism*; D008297:Male; D009318:Natriuresis; D010477:Perfusion; D011188:Potassium / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001639:Bicarbonates; D007610:Kallikreins; D011188:Potassium