Rectifying Properties of La1-XSrXMnO3/Si (x=0.2, 0.04) PN Heterostructures

La1-xSrxMnO3(x=0.2, 0.04)/Si PN heterostructures were prepared by RF magnetron sputtering method, which have evident rectifying properties. Furthermore, the excellent rectifying properties are presented in a relatively wide temperature range for La0.8Sr0.2MnO3/Si heterostructures. The diffusion voltage decreases with increasing the temperatures, which is attributed to the modulation of the interfacial electronic structure of the heterostructures.

Analysis of NaCl transport in thin ascending limb of Henle's loop in CLC-K1 null mice

To characterize the nature of NaCl transport in the thin ascending limb (tAL), we examined the transport properties of Na+ and Cl− using in vitro microperfusion of the tAL in CLC-K1 null mice. In the presence of a transmural NaCl concentration gradient (100 mM higher in the lumen), the transepithelial diffusion voltage ( V d) was 15.5 ± 1.0 and −7.6 ± 1.4 mV in CLC-K1+/+ and CLC-K1−/− mice, respectively. Neither Cl−transport inhibitor 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) nor acidification of the bathing fluid changed the V d values in CLC-K1−/−mice. The addition of 300 μg/ml protamine, a selective blocker of paracellular conductance, to the bath increased the V d values by 5.6 ± 0.7 and 12.6 ± 1.5 mV ( P < 0.001) in CLC-K1+/+ and CLC-K1−/− mice, respectively. Although efflux coefficients of 36Cl were significantly decreased in CLC-K1−/− mice (188.3 ± 25.6 in 4 tubules vs. 17.2 ± 7.0 × 10−5 cm/s in 6 tubules), those of22Na were not different between CLC-K1+/+ and CLC-K1−/− mice. These results clearly indicate that the major component of Cl− transport sensitive to NPPB or pH is mediated by CLC-K1 in the tAL.

Effect of protamine on ion conductance of ascending thin limb of Henle's loop from hamsters

To evaluate the contribution of paracellular shunt pathway in ascending thin limb (ATL) of hamsters, we examined the effect of protamine, a selective blocker of paracellular conductance, on salt-diffusion voltage (dVT) and transmural resistance (RT) during in vitro microperfusion. Lumen-negative dVT generated on reduction of lumen NaCl concentration was increased further from -7.3 +/- 0.5 to -10.3 +/- 0.7 mV when 300 micrograms/ml protamine was added to the lumen, and calculated Na+/Cl- permeability ratio was decreased from 0.46 +/- 0.03 to 0.31 +/- 0.03. Although the effect of protamine persisted after removal of the agent from the lumen, addition of 30 U/ml heparin returned the dVT toward the control level. The effect of protamine was dose dependent from 30 to 300 micrograms/ml. Protamine also exerted its effect from the bath, and the effect was inhibited by heparin either from the lumen or from the bath. The inhibitory effect was almost the same when the orientation of imposed NaCl gradient was reversed. Inhibition of transcellular Cl- transport with 0.1 mM 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) in the bath caused lumen-positive dVT. This voltage was decreased significantly by protamine. Protamine markedly decreased the apparent transference number for Na+ but slightly increased the value for Cl-. Transmural cable analysis showed that 300 micrograms/ml protamine added to the lumen increased RT from 0.59 +/- 0.10 to 1.20 +/- 0.20 omega.cm2, with the effect being reversed by 30 U/ml heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of protamine on ion conductance of upper portion of descending limb of long-looped nephron from hamsters

To estimate the contribution of paracellular shunt pathway to the cation-selective permeability in the upper portion of the descending limb of long-looped nephron (LDLu) of hamsters, we observed the effect of protamine on salt-diffusion voltage (delta VT) and transmural resistance (RT). delta VT generated on reduction of lumen NaCl concentration was decreased from 12.0 +/- 1.4 to 7.3 +/- 1.2 mV when 100 micrograms/ml protamine were added to the lumen. Although the effect of protamine persisted after removal of the agent from the lumen, addition of 30 U/ml heparin reversed the delta VT toward the control level. The effect of protamine was dose dependent in the range from 3 to 1,000 micrograms/ml. Protamine was without effect from the bath. Studies on single salt dilution voltage revealed that 100 and 300 micrograms/ml protamine inhibited relative Na+ to Cl- permeability from 4.03 +/- 0.38 to 2.14 +/- 0.21 and from 3.75 +/- 0.37 to 1.36 +/- 0.09, respectively. Protamine markedly decreased the apparent transference number for Na+ but slightly increased the value for Cl-. Protamine also inhibited permeabilities for K+, Rb+, and Li+ relative to Cl-, indicating that the inhibitory effect of protamine was not confined to Na+ but was generalized to cations. Transmural cable analysis showed that 100 micrograms/ml protamine increased RT from 14.0 +/- 1.1 to 19.3 +/- 1.2 omega.cm2, with the effect being reversed by 30 U/ml heparin. Because the effect of protamine on RT was unaffected by ouabain in the bath, changes in RT may mainly represent those of the paracellular shunt resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Cl- transport inhibitors on Cl- permeability across hamster ascending thin limb

The highly conductive Cl- transport pathway exists in the ascending thin limb (ATL) of Henle's loop. To characterize the mechanism of the Cl- conductance across the ATL, we examined effects on Cl- permeability across hamster ATL of Cl- transport inhibitors, including 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), diphenylamine carboxylate (DPC), and anthracene-9-carboxylic acid (9-AC), by the in vitro microperfusion technique. NPPB added to the bath caused reversible suppression of the relative permeability of Cl- to Na+ (PCl/PNa), as estimated from the NaCl diffusion voltage in a dose-dependent manner in a range from 3 x 10(-6) to 10(-3) M. The concentration of NPPB that inhibited PCl/PNa by 50% (ID50) was approximately 3 X 10(-5) M. When 3 X 10(-5) M NPPB was added to the bath, the lumen-to-bath flux coefficient for 36Cl (Kl----b,Cl- 10(-7) cm2/s) was decreased from 130.7 +/- 7.3 to 52.2 +/- 11.6 (n = 7, P less than 0.01). Application of NPPB in the lumen also caused reversible suppression of PCl/PNa, but this effect was less potent compared with the application of the drug via the bath. Whereas 10(-3) M 9-AC or 10(-3) M DPC decreased PCl/PNa by 6.5 +/- 1.2 and 10.2 +/- 2.6%, respectively, 3 X 10(-4) M NPPB decreased PCl/PNa by 69.7 +/- 3.8%. In maleimide-treated tubules, addition of 10(-3) M N-ethylmaleimide (NEM) increased PCl/PNa from 1.0 +/- 0.1 to 1.8 +/- 0.1 (n = 7, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

DIODE CHARACTERISTICS OF YBa2Cu3O7/n- TYPE SILICON CONTACTS

The temperature dependences of diode characteristics were measured on high-T c -superconducting YBa 2 Cu 3 O 7 (polycrystalline)/n-type silicon (monocrystalline) contacts using a common two-pole-technique at low frequencies. The non-superconducting p-type semiconductor YBa 2 Cu 3 O 6.5 (polycrystalline) served as a reference substance. The temperature coefficients of the diffusion voltage, the diffusion current and the saturation current were found to be finite at T>T c , but almost zero at T≤T c . At T=78 K , the diffusion voltage of the diode YBa 2 Cu 3 O 7/n-type silicon was about 200 mV lower as compared to that of the reference diode YBa 2 Cu 3 O 6.5/n-type silicon. The observed phenomena are explained in terms of different charge carrier behavior in the superconducting ceramics above and below T c .

Transition of permeability properties along the descending limb of long-loop nephron

The isolated segments of the hamster descending limb of the long-loop nephron (LDL) were perfused in vitro to demonstrate the axial heterogeneity with respect to permeability properties. When a NaCl gradient from the lumen to bath was present, the lumen-negative diffusion voltage (VD) was generated in the upper portion (LDLU). When the VD was measured stepwise along the axis of tubules, the magnitude of the VD decreased in the portion within 0.5 mm before the border between the outer and inner medulla in most cases, indicating that a gradual functional transition to the lower portion (LDLL) occurs along the descending limb. The lumen-to-bath flux coefficients (K1----b) for Na+ were 14.3 +/- 3.7 X 10(-7) and 2.4 +/- 0.8 X 10(-7) cm2/s in the LDLU and LDLL, respectively. The K1----b for urea were 1.7 +/- 0.6 X 10(-7) and 7.9 +/- 4.1 X 10(-7) cm2/s, respectively. The LDLL was highly permeable to water, with osmotic permeability coefficient being 1,693 +/- 517 X 10(-9) cm2.s-1.atm-1. The reflection coefficients for NaCl and urea were not different from unity. From these observations, we conclude that the functional transition occurs along the LDL from the segment with a high Na+ permeability to that with a low Na+ permeability.