Endogenous serine proteases have been reported to control the reabsorption of Na(+) by kidney- and lung-derived epithelial cells via stimulation of electrogenic Na(+) transport mediated by the epithelial Na(+) channel (ENaC). In this study we investigated the effects of aprotinin on ENaC single channel properties using transepithelial fluctuation analysis in the amphibian kidney epithelium, A6. Aprotinin caused a time- and concentration-dependent inhibition (84 +/- 10.5%) in the amiloride-sensitive sodium transport (I(Na)) with a time constant of 18 min and half maximal inhibition constant of 1 microM. Analysis of amiloride analogue blocker-induced fluctuations in I(Na) showed linear rate-concentration plots with identical blocker on and off rates in control and aprotinin-inhibited conditions. Verification of open-block kinetics allowed for the use of a pulse protocol method (Helman, S.I., X. Liu, K. Baldwin, B.L. Blazer-Yost, and W.J. Els. 1998. Am. J. Physiol. 274:C947-C957) to study the same cells under different conditions as well as the reversibility of the aprotinin effect on single channel properties. Aprotinin caused reversible changes in all three single channel properties but only the change in the number of open channels was consistent with the inhibition of I(Na). A 50% decrease in I(Na) was accompanied by 50% increases in the single channel current and open probability but an 80% decrease in the number of open channels. Washout of aprotinin led to a time-dependent restoration of I(Na) as well as the single channel properties to the control, pre-aprotinin, values. We conclude that protease regulation of I(Na) is mediated by changes in the number of open channels in the apical membrane. The increase in the single channel current caused by protease inhibition can be explained by a hyperpolarization of the apical membrane potential as active Na(+) channels are retrieved. The paradoxical increase in channel open probability caused by protease inhibition will require further investigation but does suggest a potential compensatory regulatory mechanism to maintain I(Na) at some minimal threshold value.
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http://dx.doi.org/10.1085/jgp.200509285 | DOI Listing |
Adv Sci (Weinh)
January 2025
Key Laboratory for High Efficiency Energy Conversion Science and Technology of Henan Province, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, School of Physics and Electronics, Henan University, Kaifeng, 475004, P. R. China.
Multimode luminescent materials exhibit tunable photon emissions under different excitation or stimuli channels, endowing them high encoding capacity and confidentiality for anti-counterfeiting and encryption. Achieving multimode luminescence into a stable single material presents a promising but remains a challenge. Here, the downshifting/upconversion emissions, color-tuning persistent luminescence (PersL), temperature-dependent multi-color emissions, and hydrochromism are integrated into Er ions doped CsNaYbCl nanocrystals (NCs) by leveraging shallow defect levels and directed energy migration.
View Article and Find Full Text PDFVet Med Sci
January 2025
Department of Animal Breeding and Husbandry, Istanbul University-Cerrahpasa, Istanbul, Türkiye.
Background: Obtaining information about the growth rates of animals' organs and tissues can help understand their meat production potential and determine the ideal slaughter weight (SW).
Objectives: This study aimed to determine the effects of production system and SW on the allometric growth of the non-carcass components, carcass cuts, and hind limb tissues of Kivircik lambs.
Methods: A total of 54 single-born male lambs were randomly allocated into production systems (concentrate- and pasture-based) and SW groups: 25-26 kg (LOW), 30-31 kg (MEDIUM), and 35-36 kg (HIGH).
ACS Nano
January 2025
School of Information Science and Technology and Department of Optical Science and Engineering and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai 200433, China.
The formation of large polarons resulting from the Fröhlich coupling of photogenerated carriers with the polarized crystal lattice is considered crucial in shaping the outstanding optoelectronic properties in hybrid organic-inorganic perovskite crystals. Until now, the initial polaron dynamics after photoexcitation have remained elusive in the hybrid perovskite system. Here, based on the terahertz time-domain spectroscopy and optical-pump terahertz probe, we access the nature of interplay between photoexcited unbound charge carriers and optical phonons in MAPbBr within the initial 5 ps after excitation and have demonstrated the simultaneous existence of both electron- and hole-polarons, together with the photogenerated carrier dynamic process.
View Article and Find Full Text PDFJ Vis Exp
December 2024
Department of General Surgery, Xiangyang Central Hospital, Affiliated Hospital of Hubei University of Arts and Science;
Single-incision plus one-port laparoscopic proximal gastrectomy with double-channel anastomosis (SILT-DT) is a minimally invasive surgical approach for treating proximal gastric cancer. This technique includes comprehensive laparoscopic resection of the proximal stomach, lymph node dissection, and double-tract anastomosis. By integrating single-port laparoscopic surgery with an auxiliary operating hole, SILT-DT reduces procedural difficulty while facilitating the placement of an abdominal drainage tube.
View Article and Find Full Text PDFActa Physiol (Oxf)
February 2025
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
Aim: Somatostatin from pancreatic δ-cells is a paracrine regulator of insulin and glucagon secretion, but the release kinetics and whether secretion is altered in diabetes is unclear. This study aimed to improve understanding of somatostatin secretion by developing a tool for real-time detection of somatostatin release from individual pancreatic islets.
Methods: Reporter cells responding to somatostatin with cytoplasmic Ca concentration ([Ca]) changes were generated by co-expressing somatostatin receptor SSTR2, the G-protein Gα15 and a fluorescent Ca sensor in HeLa cells.
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