Failure of 1,25-(OH)2-vitamin D3 to affect calcium flux across sheep rumen wall mucosa in vitro.

Isolated pieces of mucosa from the sheep rumen wall mounted between half-chambers were used in conventional incubation studies (1 h, 39 degrees C) with buffer solutions resembling rumen fluid (= mucosal fluid) and extracellular fluid (= serosal fluid), respectively. The mucosal-to-serosal (ms) flux of calcium was studied by use of 45CaCl2 with and without 1,25-(OH)2-vitamin D3 in the serosal incubation fluid. Different concentrations of the vitamin had no effect on Ca ms-flux.