[Structural functional and pathological aspects of the NaCl contransporter thiazide sensitive]. / Aspectos estructurales, funcionales y patológicos del cotransportador de NaCl sensible a tiazidas.

NCC cotransporter is the mayor pathway for sodium chloride reabsorption in the distal nephron and the target of thiazide diuretics which, given their clinical utility in the management of arterial hypertension, are amongst the top sold drugs in the world. NCC protein is of great physiological importance given its role in the maintenance of water and salt homeostasis on the organism. Inactivating mutations in the gene that codes for NCC cause Gitelman's syndrome: an autosomal recessive disease associated with arterial hypotension, metabolic alkalosis, hipokalemia and hypocalciuria. This syndrome represents strong evidence of the relevance of the role of NCC in blood pressure regulation, electrolyte and acid base balance. In this work we review the up to date knowledge regarding this cotransporter with special attention to the molecular aspects of the protein that determine is physiological function and pathological roles.

Platelet senescence and phosphatidylserine exposure.

BACKGROUND: The exposure of phosphatidylserine occurs during platelet (PLT) activation and during in vitro storage. Phosphatidylserine exposure also occurs during apoptosis after the release of mitochondrial cytochrome c. We have examined the role of cytochrome c release, mitochondrial membrane potential (ΔΨm), and cyclophilin D (CypD) in phosphatidylserine exposure due to activation and storage. STUDY DESIGN AND METHODS: The exposure of phosphatidylserine and the loss of ΔΨm were determined in a flow cytometer using fluorescein isothiocyanate-lactadherin and JC-1, a lipophilic cationic reporter dye. The role of CypD was determined with cyclosporin A and CypD-deficient murine PLTs. Cytochrome c-induced caspase-3 and Rho-associated kinase I (ROCK1) activation were determined by immunoblotting and using their inhibitors. RESULTS: Collagen- and thrombin-induced exposure of phosphatidylserine was accompanied by a decrease in ΔΨm. Cyclosporin A inhibited the phosphatidylserine exposure and the loss of ΔΨm. CypD(-/-) mice had decreased loss of ΔΨm and impaired phosphatidylserine exposure. Collagen and thrombin did not induce the release of cytochrome c nor the activation of caspase-3 and ROCK1. In contrast, in PLTs stored for more than 5 days, the phosphatidylserine exposure was associated with cytochrome c-induced caspase-3 and ROCK1 activation. ABT737, a BH3 mimetic that induces mitochondrial pathway of apoptosis, induced cytochrome c release and activation of caspase-3 and ROCK1 and phosphatidylserine exposure independent of CypD. CONCLUSION: These results show that in stored PLTs cytochrome c release and the subsequent activation of caspase-3 and ROCK1 mediate phosphatidylserine exposure and it is distinct from activation-induced phosphatidylserine exposure.