The neuropeptide Y (NPY) Y2 receptors and the pancreatic polypeptide Y4 receptors from rabbit kidney cortex are isolated largely as similar to 180 kDa complexes constituted of one receptor dimer and one G-protein heterotrimer, similar to NPY receptors expressed in the Chinese hamster ovary (CHO) cells. As expected, kidney and CHO cell Y2 dimers are converted into monomers by increasing concentrations of a selective agonist. Prevalence of dimeric Y2 receptors in the kidney could be related to low plasma levels of Y2 agonists, and possibly also to a relatively low concentration of Gi alpha subunits. (C) 2008 Elsevier B.V. All rights reserved.

The neuropeptide Y(NPY) Y2 receptors are detected largely as dimers in the clonal expressions in CHO cells and in particulates from rabbit kidney cortex. However, in two areas of the forebrain (rat or rabbit piriform cortex and hypothalamus), these receptors are found mainly as monomers. Evidence is presented that this difference relates to large levels of G proteins containing the Gi alpha -subunit in the forebrain areas. The predominant monomeric status of these Y2 receptors should also be physiologically linked to large synaptic inputs of the agonist NPY. The rabbit kidney and the human CHO cell-expressed Y2 dimers are converted by agonists to monomers in vitro at a similar rate in the presence of divalent cations.

Angiotensin II and the arachidonic acid metabolite derived via cytochrome P450 20-hydroxyeicostetraenoic acid promote vasoconstriction and vascular smooth muscle cell (VSMC) proliferation. This study was conducted to determine if 20-hydroxyeicostetraenoic acid contributes to angiotensin II-induced neointimal formation in balloon-injured rat carotid artery. In anesthetized rats, the drugs were infused into the clamped segment of the injured right common carotid artery for 60 minutes. The drug solution and catheter were withdrawn, the common carotid artery was ligated, and blood flow was restored. Exposure of the injured artery to angiotensin II (200 nmol/L) or arachidonic acid (10 μmol/L) increased neointimal thickening at day 14 (intima/media ratio 0.71±0.14 with vehicle versus 1.65±0.10 with angiotensin II or 1.31±0.13 with arachidonic acid; P <0.05). Cytochrome P450 4A1 antisense, but not scrambled, oligodeoxynucleotide (100 nmol/L) reduced angiotensin II-induced or arachidonic acid-induced neointimal thickening (intima/media ratio 0.90±0.07 for angiotensin II and 0.95±0.06 for arachidonic acid). 20-hydroxyeicostetraenoic acid (0.5 μmol/L) also increased neointimal thickening of injured artery (intima/media ratio 1.15±0.03); this was not altered by cytochrome P450 4A1 antisense oligodeoxynucleotide. Angiotensin II, arachidonic acid, and 20-hydroxyeicostetraenoic acid also induced the expression of cytochrome P450 4A and increased the number of CD45-positive cells; the latter effect of angiotensin II and arachidonic acid, but not 20-hydroxyeicostetraenoic acid, was diminished by cytochrome P450 4A1 antisense oligodeoxynucleotide. These data suggest that arachidonic acid metabolites derived via cytochrome P450 4A, most likely 20-hydroxyeicostetraenoic acid, mediate angiotensin II-induced neointimal thickening in injured rat carotid artery.

ArticleA STUDY OF THE INORGANIC CONSTITUENTS OF THE BODY WITH RESPECT TO THEIR STIMULATING EFFECT ON SUGAR METABOLISMW. E. Burge, and A. M. EstesW. E. BurgeFrom the Department of Physiology, University of Illinois, Urbana, Illinois, and A. M. EstesFrom the Department of Physiology, University of Illinois, Urbana, IllinoisPublished Online:01 May 1928https://doi.org/10.1152/ajplegacy.1928.85.1.103MoreSectionsPDF (393 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation More from this issue > Volume 85Issue 1May 1928Pages 103-105 Copyright & PermissionsCopyright © 1928 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1928.85.1.103History Received 12 March 1928 Published online 1 May 1928 Published in print 1 May 1928 Metrics

1. The optically active amino acids stimulate sugar metabolism in the plant cell, spirogyra, and the animal cell, paramecium, while the optically inactive ones do not. 2. Paramecium uses sugar much more rapidly than spirogyra, in keeping with the more intense metabolism in animals than in plants. 3. Spirogyra and paramecium use dextrose and levulose more rapidly than galactose, just as is the case with higher animals and man. 4. Insulin increases the rate of utilization of the sugars in paramecium and spirogyra, similar to its action in the higher animals and man.

According to most investigators (1) adrenalin increases heat production and raises the respiratory quotient, thus indicating an increase in sugar metabolism. The object of this investigation was to determine directly the effect of adrenalin on sugar metabolism. Practically all the work that has been carried out with adrenalin has been done on the mammal with its various organs and glands of internal secretion where the situation is very complex. In this investigation we have attempted to simplify matters by using single celled animals and adding the adrenalin directly to the sugar solutions containing these animal cells and studying the effect on the rate of sugar utilization. The animal cell used was Paramecium caudatum. The paramecia were raised in great numbers on an infusion of alfalfa, pond lily leaves, and lake water. They were collected and washed free of debris by the use of a small centrifugalizing machine. The mitrifugalizing tubes were graduated in cubic centimeters, so the paramecia were measured as they were collected. Sugar determinations were made according to the method of Benedict. Air was kept bubbling through the liquid containing the paramecia to insure an adequate supply of oxygen.