Kuniaki Yoshitomi

Learn More
Although vasopressin V1 receptors have been shown to exist in both luminal and basolateral membranes of rabbit cortical collecting duct (CCD), exact cell types having V1 receptors remain unestablished. To identify the distribution of V1 receptor by cytoplasmic Ca2+ response, we utilized the confocal imaging system in the microperfused rabbit CCD.(More)
In this paper we study the operator H β = −∆ − βδ(· − Γ) in L 2 (R 2), where Γ is a smooth periodic curve in R 2. We obtain the asymptotic form of the band spectrum of H β as β tends to infinity. Furthermore, we prove the existence of the band gap of σ(H β) for sufficiently large β > 0. Finally, we also derive the spectral behaviour for β → ∞ in the case(More)
To examine the nature of ion-conductive pathways in the basolateral membrane of rabbit distal convoluted tubule (DCT), we recorded single-channel currents from the tubule segment isolated from collagenase-treated kidney. Using cell-attached patch pipettes filled with 130 mM KCl, 5.4 mM CaCl2, and 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (pH(More)
Given n ≥ 2, we put r = min{ i ∈ N; i > n/2 }. Let Σ be a compact, C r-smooth surface in R n which contains the origin. Let further {S ǫ } 0≤ǫ<η be a family of measurable subsets of Σ such that sup x∈Sǫ |x| = O(ǫ) as ǫ → 0. We derive an asymptotic expansion for the discrete spectrum of the Schrödinger operator −∆ − βδ(· − Σ \ S ǫ) in L 2 (R n), where β is a(More)
By cable analysis and intracellular microelectrode impalement in the in vitro perfused renal tubule, we identified alpha- and beta-intercalated (IC) cells along the rabbit distal nephron segments, including the connecting tubule (CNT), the cortical collecting duct (CCD), and the outer medullary collecting duct in the inner stripe (OMCDi). IC cells were(More)
The epithelia of the medullary thick ascending limb (MAL) consists of two cell types, high (HBC) and low basolateral conductance (LBC) cell, depending on the K+ conductance of the basolateral membrane. The NH4+ conductance distinct from the K+ conductance has been suggested to exist in the proximal tubule, MAL cell, and Xenopus oocyte. The present study was(More)
We investigate the two-dimensional magnetic Schrödinger operator H B,β = (−i∇ − A) 2 − βδ(· − Γ), where Γ is a smooth loop and the vector potential A corresponds to a homogeneous magnetic field B perpendicular to the plane. The asymptotics of negative eigenvalues of H B,β for β → ∞ is found. It shows, in particular, that for large enough positive β the(More)
To clarify the mechanism of action of arginine vasopressin (AVP) on ionic conductances, electrophysiological technique was applied to the rabbit cortical collecting duct (CCD) perfused in vitro. When AVP (100 pM) was added to the bath, transepithelial voltage (VT), transepithelial resistance (RT), and fractional resistance of the apical membrane (fRA) of(More)
Recently we clarified the mechanism in which arginine-vasopressin (AVP) applied from the luminal side inhibits the basolateral Cl- conductance, which is stimulated by basolateral AVP. However, to prove that these vasopressin phenomena are expressed via receptor mediated actions, we examined the effect of specific V1 and V2 receptor antagonists, OPC-21268(More)
Effects of ambient Ca2+ concentration on Cl- transport across the thin ascending limb of Henle's loop (TAL) were examined by the in vitro microperfusion technique. When Ca2+ concentration in the bathing fluid was decreased from 1.5 mM to nominally 0 mM at 37 degrees C, the relative permeability of Cl- to Na+ (PCl/PNa) estimated from the NaCl diffusion(More)