Kinetics of calcium fluxes across the intestinal mucosa of the marine teleost, Gadus morhua, measured using an in vitroperfusion method

• Main Authors: Sundell, Bjorn Thrandur Bjornsson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1988
• Subjects: atlantic cod; Gadus morhua
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.580.4487; http://jeb.biologists.org/content/140/1/171.full.pdf

An in vitro technique for perfusion of the intestinal vasculature and lumen was developed and used to measure calcium (Ca2+) fluxes across the intestinal mucosa of the marine teleost, the Atlantic cod {Gadus morhua). Saturable and nonsatur-able components of the calcium influx and efflux were determined. The calcium influx had one passive component and one saturable component, following Michaelis-Menten kinetics with Km = 8-41mmoll~1 and Vmax = 0-604 /rniolCa2"1 " kg"1 h"1. At physiological Ca2+ concentrations in the vascular ([Ca2+] = l-9mmoir1) and luminal ([Ca2+] = U-9mmoWl) perfusion fluids, the saturable component amounted to 60 % of the Ca2+ influx. The high-affinity Ca2+-ATPase inhibitor chlorpromazine (CP, 10~4moll~1) antagonized 45 % of the Ca2+ influx. The Ca2+ efflux across the intestinal mucosa of the cod was a saturable process, following Michaelis-Menten kinetics with Km =6-15mmoll~1 and Vmax = 3-79JumolCa2+kg-1h-1, but insensitive to CP ( lO^molP 1). The Ca2+ efflux was l-22jumolCa2+ kg"1 h"1, representing about 20 % of the total calcium excretion and about 50 % of the extrarenal excretion of the Atlantic cod in vivo.