Several phosphate transport processes are present in vascular smooth muscle cells.

Several phosphate transport processes are present in vascular smooth muscle cells. Am J Physiol Heart Circ Physiol. 2019 Dec 30;: Authors: Hortells L, Guillén N, Sosa C, Sorribas V Abstract We have studied Pi handling in rat aortic vascular smooth muscle cells (VSMC) using 32P-radiotracer assays. Our results have revealed a complex set of mechanisms consisting in 1) well-known PiT1/PiT2-mediated sodium-dependent Pi transport; 2) Slc20-unrelated sodium-dependent Pi transport that is sensitive to the stilbene derivatives 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and (4-acetamido-4-isothiocyanostilbene-2,2-disulfonate) (SITS); 3) a sodium-independent Pi uptake system that is competitively inhibited by sulfate, bicarbonate, and arsenate and is weakly inhibited by DIDS, SITS, and phosphonoformate; and 4) an exit pathway from the cell that is partially chloride-dependent and unrelated to the known anion-exchangers expressed in VSMC. The inhibitions of sodium-independent Pi transport by sulfate and of sodium-dependent transport by SITS were studied in greater detail. The maximal inhibition by sulfate was similar to that of Pi itself, with a very high inhibition constant (212 mM). SITS only partially inhibited sodium-dependent Pi transport, but the Ki was very low (14 µM). Nevertheless, SITS and DIDS did not inhibit Pi transport in Xenopus laevis oocytes expressing PiT1 or PiT2. Both the sodium-dependent and sodium-indepen...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Tags: Am J Physiol Heart Circ Physiol Source Type: research