No abstract

Cortical collecting duct cells were cultured on permeable membranes and used to assess cellular transport properties for calcium/cadmium. Functional viability of the cells in culture were affirmed by their ability to absorb sodium and chloride, secrete proton! and potassium, and respond appropriately to the hormones vassopressin and aldosterone. Calcium absorption by these cells was affected neither by sodium blockers or hormone inducers of cyclic Aý!P nor, surprisingly, by various calcium channel blockers. However when the pH of the culture medium on the apical side of the cells was controlled artificially by buffer, calcium absorption was found to be affected. Decreasing the pH inhibited calcium uptake by cells, indicating that calcium and H+ transport were linked possibly by a mechanism involving a 11+/Ca-H-ex 'changer. Cadmium had no apparent effect on calcium absorption untill cadmium concentrations reached levels at which nonspecific, cytotoxic effects were observed. In another separate project, initial research efforts were undertaken to use electron paramagnetic resonance (EPR) to explain the mechanism by which endothelial/smooth muscle cells release the putative endothelium-derived relaxing factor (EDRF), nitric oxide (NO), from vasodilator druigs. EPR detection on NO was accomplished when the model drug nitroprusside was chemically reduced in a cell- 29 0059TI -3. SI QA 4~ 40L."~f , ZSh#97UMOM