Bone lengthening during skeletal growth is driven primarily by the controlled enlargement of growth plate (GP) chondrocytes. The cellular mechanisms are unclear but membrane transporters are probably involved. We investigated the role of the Na(+)/H(+) antiporter (NHE1) and anion exchanger (AE2) in bone lengthening and GP chondrocyte hypertrophy in Sprague-Dawley 7-day-old rat (P7) bone rudimen...

PURPOSE Bicarbonate transport plays a role in aqueous humor (AH) secretion. The authors examined bicarbonate transport mechanisms and carbonic anhydrase (CA) in porcine nonpigmented ciliary epithelium (NPE). METHODS Cytoplasmic pH (pH(i)) was measured in cultured porcine NPE loaded with BCECF. Anion exchanger (AE), sodium bicarbonate cotransporter (NBC), and CA were examined by RT-PCR and imm...

BACKGROUND The ionic mechanism underlying the transient inward current (I(ti)), the current responsible for delayed afterdepolarizations (DADs), appears to be different in ventricular myocytes and Purkinje fibers. In ventricular myocytes, I(ti) was ascribed to a Na(+)-Ca(2+) exchange current, whereas in Purkinje fibers, it was additionally ascribed to a Cl(-) current and a nonselective cation c...

OBJECTIVES To identify key determinants explaining country-year variations in antibiotic use and resistance. METHODS Ambulatory antibiotic use data [in defined daily doses per 1000 inhabitants per day (DIDs)] for 19 European countries from 1999 to 2007 were collected, along with 181 variables describing countries in terms of their agriculture, culture, demography, disease burden, education, h...

This study examined the effect of hyposmotic solutions on the syncytiotrophoblast microvillous membrane potential ( E m) in mature intermediate villi isolated from term human placentas. When villi were exposed to a control solution (280 mosmol/kgH2O; 116 mM NaCl) and then to either a 138-hyposmotic (138 mosmol/kgH2O; 37 mM NaCl) or 170-hyposmotic (170 mosmol/kgH2O; 55 mM NaCl) solution, there w...

Nitrate transport in excised corn (Zea mays L.) roots was inhibited by phenylglyoxal, but not by 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS) or fluorescein isothiocyanate (FITC). Inhibition of nitrate uptake by a 1-hour treatment with 1 millimolar phenylglyoxal was reversed after 3 hours, which was similar to the time needed for induction of nitrate uptake. If induction of nitrate ...

Birdsey, T. J., R. D. H. Boyd, C. P. Sibley, and S. L. Greenwood. Effect of hyposmotic challenge on microvillous membrane potential in isolated human placental villi. Am. J. Physiol. 276 (Regulatory Integrative Comp. Physiol. 45): R1479–R1488, 1999.—This study examined the effect of hyposmotic solutions on the syncytiotrophoblast microvillous membrane potential (Em) in mature intermediate villi...

Pulmonary artery smooth muscle cell (PASMC) proliferation contributes to increased pulmonary vascular resistance and pulmonary hypertension. Because proliferation depends on membrane potential (V(m)) and because V(m) is, in part, determined by Cl(-) currents (I(Cl)), we examined the effects of I(Cl) inhibition with 4,4;-diisothiocyanatostilbene-2,2;-disulfonic acid (DIDS) on cultured rat PASMCs...