Effects of a high-sodium diet on renal tubule Ca2+ transporter and claudin expression in Wistar-Kyoto rats

Background: Urinary Ca^{2+} excretion increases with dietary NaCl. NaCl-induced calciuria may be associated with hypertension, urinary stone formation and osteoporosis, but its mechanism and long-term effects are not fully understood. This study examined alterations in the expressions of renal Ca^{2+} transporters, channels and claudins upon salt loading to better understand the mechanism of salt-induced urinary Ca^{2+} loss. Methods: Eight-week old Wistar-Kyoto rats were fed either 0.3% or 8% NaCl diet for 8 weeks. Renal cortical expressions of Na+/Ca2+ exchanger 1 (NCX1), Ca^{2+} pump (PCMA1b), Ca^{2+} channel (TRPV5), calbindin-D28k, and claudins (CLDN-2, -7, -8, -16 and −19) were analyzed by quantitative PCR, western blot and/or immunohistochemistry. Results: Fractional excretion of Ca^{2+} increased 6.0 fold with high-salt diet. Renal cortical claudin-2 protein decreased by approximately 20% with decreased immunological staining on tissue sections. Claudin-16 and −19 expressions were not altered. Renal cortical TRPV5, calbindin-D28k and NCX1 expressions increased 1.6, 1.5 and 1.2 fold, respectively. Conclusions: Chronic high-salt diet decreased claudin-2 protein and increased renal TRPV5, calbindin-D28k, and NCX1. Salt loading is known to reduce the proximal tubular reabsorption of both Na+ and Ca^{2+}. The reduction in claudin-2 protein expression may be partly responsible for the reduced Ca^{2+} reabsorption in this segment. The concerted upregulation of more distal Ca^{2+}-transporting molecules may be a physiological response to curtail the loss of Ca^{2+}, although the magnitude of compensation does not seem adequate to bring the urinary Ca^{2+} excretion down to that of the normal-diet group

Characteristic expressions of GABA receptors and GABA producing/transporting molecules in rat kidney.

Gamma-aminobutyric acid (GABA) is an important neurotransmitter, but recent reports have revealed the expression of GABAergic components in peripheral, non-neural tissues. GABA administration induces natriuresis and lowers blood pressure, suggesting renal GABA targets. However, systematic evaluation of renal GABAergic components has not been reported. In this study, kidney cortices of Wistar-Kyoto rats (WKY) were used to assay for messenger RNAs of GABA-related molecules using RT-PCR. In WKY kidney cortex, GABAA receptor subunits, α1, β3, δ, ε and π, in addition to both types of GABAB receptors, R1 and R2, and GABAC receptor ρ1 and ρ2 subunit mRNAs were detected. Kidney cortex also expressed mRNAs of glutamate decarboxylase (GAD) 65, GAD67, 4-aminobutyrate aminotransferase and GABA transporter, GAT2. Western blot and/or immunohistochemistry were performed for those molecules detected by RT-PCR. By immunofluorescent observation, co-staining of α1, β3, and π subunits was observed mainly on the apical side of cortical tubules, and immunoblot of kidney protein precipitated with π subunit antibody revealed α1 and β3 subunit co-assembly. This is the first report of GABAA receptor π subunit in the kidney. In summary, unique set of GABA receptor subunits and subtypes were found in rat kidney cortex. As GABA producing enzymes, transporters and degrading enzyme were also detected, a possible existence of local renal GABAergic system with an autocrine/paracrine mechanism is suggested

The rationale and design of reduction of uncontrolled hypertension by Remote Monitoring and Telemedicine (REMOTE) study

Purpose: Although self-measurement of home blood pressure (HBP) is common in Japan and HBP telemonitoring via the Internet is possible, whether telemonitoring improves HBP control better than conventional practice remains unclear. Furthermore, hypertension care with online communication using telemonitored HBP is feasible, whereas the efficacy and safety of such telemedicine have not been established. We aim to compare traditional care, care with office visits using HBP telemonitoring, and antihypertensive telemedicine based on HBP telemonitoring. Methods and design: In total, 444 patients with uncontrolled hypertension will be recruited and randomly assigned to three groups: (1) control: usual care with office visits and HBP self-report, (2) telemonitoring: weekly assessment of transmitted HBP by physicians and treatment adjustment upon office visits, or (3) telemedicine: online communication instead of office visits to adjust medication using telemonitored HBP. Primary outcome is the time to control of HBP, and secondary outcomes include achieved HBP levels, adherence, treatment intensity, adverse events, patient satisfaction and cost-effectiveness. Discussion: Hypertension care with telemonitoring and telemedicine are expected to require shorter time to achieve HBP control compared to usual care. Combining HBP telemonitoring with telemedicine may lower the hurdles for starting and persisting to hypertension treatment and eventually reduce cardiovascular events

The rationale and design of reduction of uncontrolled hypertension by Remote Monitoring and Telemedicine (REMOTE) study

Although self-measurement of home blood pressure (HBP) is common in Japan and HBP telemonitoring via the Internet is possible, whether telemonitoring improves HBP control better than conventional practice remains unclear. Furthermore, hypertension care with online communication using telemonitored HBP is feasible, whereas the efficacy and safety of such telemedicine have not been established. We aim to compare traditional care, care with office visits using HBP telemonitoring, and antihypertensive telemedicine based on HBP telemonitoring.status: publishe

GABA_C receptor subunits are expressed in rat kidney.

<p>A) RT-PCR results for GABA_C receptor subunits in rat kidney cortex. Appropriately-sized bands were detected for GABA_C receptor ρ1 and ρ2 subunits in at least five independent experiments. Rat brain RNA or commercial universal RNA was used as positive control. M: molecular marker. B) Immunoblotting for GABA_C receptor ρ1 and ρ2 subunits in rat kidney cortex. B: brain control, K: kidney cortex.</p

GABA_B receptor R1 and R2 subtypes are expressed in rat kidney.

<p>A) RT-PCR results for GABA_B receptor subtypes in rat kidney cortex. Appropriately-sized bands were detected for GABA_B receptor R1 and R2 subtypes in at least five independent experiments. Rat brain RNA or commercial universal RNA was used as positive control. M: molecular marker. B) Immunostaining for GABA_B receptor R1 and R2 subtypes in rat kidney cortex. Staining with normal IgG instead of primary antibody served as negative control.</p