The action of iontophoretically applied L‐glutamate on an insect visceral muscle
作者:
Stuart J. Dunbar,
Tom Piek,
期刊:
Archives of Insect Biochemistry and Physiology
(WILEY Available online 1983)
卷期:
Volume 1,
issue 1
页码: 93-103
ISSN:0739-4462
年代: 1983
DOI:10.1002/arch.940010110
出版商: Wiley Subscription Services, Inc., A Wiley Company
关键词: glutamate;insect;δ‐philanthotoxin;iontophoresis;visceral muscle;Locusta migratoria;proctolin
数据来源: WILEY
摘要:
Abstract1) lontophoretic application of L‐glutamate was employed to study the distribution of glutamate receptors in the superior longitudinal (SL) muscles of the locust (Locusta migratoria) hindgut, in which spontaneous activity was inhibited using normal saline containing 5 mM MgCl2.2) Junctional glutamate potentials with a rise time of 50–100 ms (peak) and a decay time of 250–400 ms were recorded at localized sites using ejection pulses in the range 5–10 nC. Most active sites were found in interfiber clefts and were spaced at about 250–300 μm intervals. 3) Desensitization of glutamate receptors occurred using ejection frequencies>0.2 Hz. Desensitization could be irreversibly blocked using the lectin concanavalin A. 4) Depolarizing (D‐) and biphasic depolarizing/hyperpofarizing (DH ‐) extrajunctional glutamate potentials were observed using ejection pulses>15 nC. 5) δ‐Philanthotoxin (δ‐PTX) at concentrations>0.3 Uml−1inhibited junctional glutamate potentials in a dose‐dependent manner, 50% inhibition was achieved using 0.45 Uml−1δ‐PTX. 6) Subthreshold concentrations of proctolin (up to 5 × 10−10M) had no visible effect on glutamate potentials, suggesting that proctolin possibly does not act by modulating glutamate activity. 7) It is proposed that glutamate plays a transmitter role in SL muscles, while the ro
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