Subject(s)
Cyclosporine/adverse effects , Immunosuppressive Agents/adverse effects , Kidney Transplantation/immunology , Administration, Oral , Adolescent , Adult , Aged , Creatinine/blood , Cyclosporine/administration & dosage , Double-Blind Method , Female , Humans , Immunosuppressive Agents/administration & dosage , Kidney Transplantation/physiology , Male , Middle Aged , Safety , Time FactorsABSTRACT
Hypercalciuria has been observed in human and experimental hypertension. The distal convoluted tubule (DCT) is the site of fine regulation for Ca2+ excretion. We assessed the cellular factors responsible for Ca2+ reabsorption in the DCT of spontaneously hypertensive rats (SHR). Vitamin D3 dependent Ca-binding protein 28k (CaBP28k), a factor involved in Ca2+ influx, and plasma membrane Ca ATPases (PMCA), a factor involved in Ca2+ efflux, were studied in hypertensive 16-week-old SHR and normotensive Wistar-Kyoto rats (WKY). mRNA levels for CaBP28k, PMCA 2 and PMCA 4 were not different in the two strains. However, CaBP28k protein was more abundant, and PMCA protein was less abundant in SHR than in WKY. PMCA antibody recognized only DCT in the two strains. In conclusion, decreased PMCA in DCT may be responsible for the hypercalciuria in SHR.
Subject(s)
Calcium/metabolism , Hypertension/metabolism , Kidney/metabolism , Animals , Blotting, Western , Calbindins , Calcium-Transporting ATPases/metabolism , Cell Membrane/enzymology , Hypertension/enzymology , Hypertension/genetics , Immunohistochemistry , Kidney/enzymology , Kidney Tubules, Distal/enzymology , Kidney Tubules, Distal/metabolism , Male , RNA, Messenger/analysis , RNA, Messenger/biosynthesis , Rats , Rats, Inbred SHR , Rats, Inbred WKY , S100 Calcium Binding Protein G/metabolismABSTRACT
Calcium ions (Ca2+) are involved in the regulation of many cellular activities. The Ca-ATPase(s) of the plasma membrane and of the endoplasmic reticulum play an important role in controlling the intracellular Ca2+ concentration. Therefore, it is not unexpected that these enzymes are modulated by different factors. The activity of the plasma membrane Ca-ATPase is modified by the amount of negatively charged phospholipids surrounding the enzyme. The regulation of the endoplasmic reticulum Ca-ATPase depends on the phosphorylation of phospholamban by cAMP- and cGMP-dependent protein kinase. These two different Ca2+ transport ATPases are present in both visceral and vascular smooth muscle, but tissue- and species-dependent differences in their relative amount have been observed. In this article we will review the characteristics of Ca-ATPases of the smooth muscle.
