| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
The Journal of Neurophysiology Vol. 80 No. 2 August 1998,
pp. 771-784
Copyright ©1998 The American Physiological Society
Physiological Institute, Neuroendocrinology Working Group, University of Marburg, 35037 Marburg, Germany
Walther, Christian, Klaus E. Zittlau, Harald Murck, and Karlheinz Voigt. Resting membrane properties of locust muscle and their modulation. I. Actions of the neuropeptides YGGFMRFamide and proctolin. J. Neurophysiol. 80: 771-784, 1998. The resting K+ conductance (GK,r) of locust jumping muscle and its modulation by two neuropeptides, proctolin (Arg-Tyr-Leu-Pro-Thr) and YGGFMRFamide (Tyr-Gly-Gly-Phe-Met-Arg-Phe-NH2), were investigated using the two-electrode voltage clamp. At a physiological [K+]o of 10 mM, GK,r accounts for ~90% of the membrane resting conductance, and the resting membrane potential differs by 
1 mV from EK (mean: 
74 mV). There is a K+ conductance that slowly activates on hyperpolarization (GK,H) and that seems to be largely located in the transverse tubules. Steady-state activation of GK,H was analyzed by tail current measurements. GK,H is activated partially at EK but accounts for probably 50% of total resting K+ conductance. Raising [K+]o caused a large increase in GK,r and in maximal steady state GK,H without shifting the voltage sensitivity of GK,H. YGGFMRFamide and proctolin reduce GK,H, mainly affecting the maximal steady-state conductance. The voltage-insensitive component of the resting K+ conductance is also reduced. The conductance suppressed by the peptides exhibited an outwardly rectifying instantaneous current/voltage-characteristic that is quite similar to that of GK,H. The actions of the two peptides appeared to be identical, but proctolin was by some two orders of magnitude more potent than YGGFMRFamide. The effects of both peptides are mediated by G proteins. They are mimicked by phorbol esters but do not seem to be initiated by either branch of the phospholipase C-dependent intracellular pathways. The properties of the resting K+ conductance in locust muscle and other invertebrate muscles are compared. The biological significance of peptide-induced reduction in resting K+ conductance is discussed in view of the known property of proctolin to support tonic force as opposed to FMRFamide-peptides that support quick leg movements.
This article has been cited by other articles:
|
|
 |
|
  U. Rose, C. Derst, M. Wanischeck, C. Marinc, and C. Walther Properties and possible function of a hyperpolarisation-activated chloride current in Drosophila J. Exp. Biol., July 15, 2007; 210(14): 2489 - 2500. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Philipp, N. Rogalla, and S. Kreissl The neuropeptide proctolin potentiates contractions and reduces cGMP concentration via a PKC-dependent pathway J. Exp. Biol., February 1, 2006; 209(3): 531 - 540. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. L. Wilkens, T. Shinozaki, T. Yazawa, and H. E. D. J. ter Keurs Sites and modes of action of proctolin and the FLP F2 on lobster cardiac muscle J. Exp. Biol., February 15, 2005; 208(4): 737 - 747. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Brustle, S. Kreissl, D. L. Mykles, and W. Rathmayer The neuropeptide proctolin induces phosphorylation of a 30 kDa protein associated with the thin filament in crustacean muscle J. Exp. Biol., January 8, 2001; 204(15): 2627 - 2635. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Wegener and D. R. Nassel Peptide-Induced Ca2+ Movements in a Tonic Insect Muscle: Effects of Proctolin and Periviscerokinin-2 J Neurophysiol, December 1, 2000; 84(6): 3056 - 3066. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Walther and K. E. Zittlau Resting Membrane Properties of Locust Muscle and Their Modulation II. Actions of the Biogenic Amine Octopamine J Neurophysiol, August 1, 1998; 80(2): 785 - 797. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
