QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Uesaka, T. Articles by Ando, M. Search for Related Content PubMed PubMed Citation Articles by Uesaka, T. Articles by Ando, M. Social Bookmarking                         What's this?

Glucagon-like peptide isolated from the eel intestine: effects on atrial beating

Toshihiro Uesaka^1,3, Keiichi Yano², Seiji Sugimoto² and Masaaki Ando^1,*

¹ Laboratory of Integrative Physiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan,
² Tokyo Research Laboratories, Kyowa Hakko Kogyo Co. Ltd, 3-6-6 Asahimachi, Machidashi, Tokyo 194-0023, Japan and
³ Department of Environment and Mutation, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan

View larger version (44K): [in a new window]   Fig. 1. Final HPLC purification of EI-14 obtained from eel gut. (A) The active fraction obtained by chromatographic steps was subjected to reverse-phase HPLC (TSK ODS-80TM column) and eluted isocratically with 26.5% acetonitrile in 5% 2-propanol and 0.1% trifluoroacetic acid (pH 2.2). The flow rate was 0.5mlmin-1. (B) Effects of purified EI-14 on atrial beating and contractile force.

View larger version (16K): [in a new window]   Fig. 2. A comparison of the chemical characteristics of native (N) and synthetic (S) EI-14. (A) Reverse-phase chromatograms of N, S and N+S using the TSK ODS-120T column. N, S and N+S were eluted with a 50min linear gradient of 20%–30% acetonitrile in 10% 2-propanol and 0.1% trifluoroacetic acid. The flow rate was 0.5mlmin-1. (B) Cation-exchange chromatograms. Each peptide was eluted with a 25min linear gradient of 0-0.5moll-1 NaCl in 10% ethanol and 20mmoll-1 phosphate buffer (pH 6.7). The flow rate was 0.5mlmin-1.

View larger version (16K): [in a new window]   Fig. 3. Concentration–response curve for the effects of synthetic EI-14 on atrial beating. (A) The change in contractile force after addition of EI-14 plotted against its corresponding concentration (logarithmic scale). The control value before addition of EI-14 was 14.34±1.95mN (N=13). Values are means ± S.E.M. The number of experiments at each concentration is indicated in parentheses. (B) The effect of EI-14 on atrial beating rate. The control value was 69.5±6.6beatsmin-1 (N=13). The sample size is the same as in A.

View larger version (24K): [in a new window]   Fig. 4. Oscillation of intracellular Ca2+ concentration ([Ca2+]i) in a region of the atrial myocardium. The [Ca2+]i was determined by measuring the brightness of all pixels (N=1200) in the region, and the mean brightness ± S.E.M. was obtained. Error bars were all smaller than the size of the symbol. EI-14 (10-7moll-1) was applied at time zero.

View larger version (44K): [in a new window]   Fig. 5. Effects of extracellular Ca2+ on atrial beating. (A) Representative control response after treatment with synthetic EI-14 in normal Ringer’s solution. EI-14 (10-7moll-1) was applied during the period indicated by the horizontal bar. (B) Effects of EI-14 in the absence of Ca2+ in the bathing medium. Ca2+ was omitted during the period indicated by the horizontal bar (Ca2+-free). (C) Effects of EI-14 after pretreatment with verapamil. Verapamil (10-5moll-1) was applied during the period indicated by the horizontal bar.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter