The widespread presence of the Na-K-2Cl (NKCC) cotransporter protein suggests that chronic administration of inhibitors may result in adverse effects. Inhibition of the NKCC cotransporter by loop diuretics is felt to underlie the diuretic and the pulmonary smooth muscle relaxant effects of this drug class. However, the fundamental regulation of salt and water movement by this cotransporter sugg...

We studied the phosphorylation of the secretory Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) in rat parotid acinar cells. We have previously shown that NKCC1 activity in these cells is dramatically upregulated in response to beta-adrenergic stimulation and that this upregulation correlates with NKCC1 phosphorylation, possibly due to protein kinase A (PKA). We show here that when ATP is added to puri...

Marked Na(+)/Li(+) countertransport hyperactivity and post-load hyperinsulinaemia have been described in 93% of patients with cardiac syndrome X. We hypothesized that more complex abnormalities in Na(+) traffic across the cell membrane are present in these patients. The aim of the present study was to evaluate the activities of the two main transporters responsible for transmembrane Na(+) trans...

Though diabetes is a disease with vascular complications, little is known about its effects on the blood-brain barrier or the blood-cerebrospinal fluid barrier (BCSFB). The BCSFB is situated at choroid plexuses located in the lateral, third, and fourth ventricles. Choroid plexuses are the primary site of cerebrospinal fluid (CSF) production and express numerous ion transporters. Previous studie...

Previously we showed that atrial natriuretic factor (ANF) decreases cardiac cell volume by inhibiting ion uptake by Na+/K+/2Cl- cotransport. Digital video microscopy was used to study the role of guanosine 3',5'-monophosphate (cGMP) in this process in rabbit ventricular myocytes. Each cell served as its own control, and relative cell volumes (volume(test)/volume(control)) were determined. Expos...

The esophageal submucosal glands (SMG) secrete HCO(3)(-) and mucus into the esophageal lumen, where they contribute to acid clearance and epithelial protection. This study characterized the ion transport mechanisms linked to HCO(3)(-) secretion in SMG. We localized ion transporters using immunofluorescence, and we examined their expression by RT-PCR and in situ hybridization. We measured HCO(3)...

In cortical collecting ducts (CCDs) perfused in vitro, inhibiting the epithelial Na(+) channel (ENaC) reduces Cl(-) absorption. Since ENaC does not transport Cl(-), the purpose of this study was to determine how ENaC modulates Cl(-) absorption. Thus, Cl(-) absorption was measured in CCDs perfused in vitro that were taken from mice given aldosterone for 7 days. In wild-type mice, we observed no ...

NaCl and Na/K/Cl co-transport systems in many cell types show a number of similarities, among which are sensitivity to 'loop' diuretic inhibition and extremely high anion selectivity. Avian erythrocytes possess a NA+K+2Cl co-transporter that is stimulated by agents raising intracellular cAMP. The system is also inhibited following ATP-depletion of the cells, in agreement with results in other t...

The purpose of the present study was to analyze the long-term regulation of renal bumetanide-sensitive Na+-K+-2Cl- cotransporter and thiazide-sensitive Na+-Cl- cotransporter gene expression during changes in NaCl and water metabolism. Male Wistar rats exposed to high or low NaCl intake, saline loading, dehydration, water loading, and furosemide administration during 7 days were studied. Control...