PMID- 2443695
OWN - NLM
STAT- MEDLINE
DCOM- 19871119
LR  - 20190510
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 388
DP  - 1987 Jul
TI  - Suppression of calcium current by an endogenous neuropeptide in neurones of 
      Aplysia californica.
PG  - 565-95
AB  - 1. Actions of the neuropeptide FMRFamide (Phe-Met-Arg-Phe-NH2) and its derivative 
      YGG-FMRFamide (Tyr-Gly-Gly-Phe-Met-Arg-Phe-NH2) on Ca2+ current were examined in 
      identified, voltage-clamped neurones in the abdominal ganglion of Aplysia 
      californica. 2. 'Puffed' application of either peptide at concentrations of 1-50 
      microM was followed by a transient partial suppression of pharmacologically 
      isolated inward Ca2+ current elicited by a depolarizing step. At 20 degrees C, 
      suppression was maximal 10-25 s following the brief puff of peptide, and lasted 
      up to 90 s. Bath application of peptide had a steady suppressing effect, showing 
      little if any desensitization. 3. Alternative sources of inward current 
      suppression were ruled out, indicating that application of FMRFamide or 
      YGG-FMRFamide produces a true decrease in Ca2+ current, rather than enhancement 
      of possible contaminating outward (K+, H+ or Cl-) currents. 4. FMRFamide and 
      YGG-FMRFamide were equally effective in suppressing Ca2+ current (apparent 
      dissociation constant, KD* approximately 10 microM). However, only 30-50% of the 
      total Ca2+ current elicited by voltage steps to above +10 mV appeared to be 
      susceptible to suppression by even saturating concentrations of peptide. This, as 
      well as a reduced effect of the peptides on Ca2+ current which was observed at 
      potentials below +10 mV, may perhaps result from the presence of more than one 
      class of Ca2+ channels, only one of which is sensitive to FMRFamide. 5. FMRFamide 
      eliminated a constant fraction of Ca2+ current at all potentials above +10 mV, 
      and had no direct effect on activation or inactivation of the remaining current. 
      This behaviour is consistent with reduction in the number of functional Ca2+ 
      channels by the peptide. 6. Suppression of Ca2+ current produced a concomitant 
      depression of Ca2+-dependent K+ current, which was shown previously to be 
      insensitive to FMRFamide when activated by direct ionophoretic injection of Ca2+ 
      into the cell. 7. The effect of FMRFamide on Ca2+ current was normal following 
      interference with or activation of known second-messenger systems, those 
      involving adenosine 3',5'-cyclic monophosphate (cyclic AMP), cyclic GMP, Ca2+, 
      inositol trisphosphate and protein kinase C. 8. Suppression of Ca2+ current by 
      FMRFamide appeared to be mediated by the same receptor as enhancement by the 
      peptide of K+ current resembling IK(S) (K+ current suppressed by serotonin), an 
      effect seen in most of the same cells. Both effects of FMRFamide were mimicked by 
      injection of guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S) into the cell, 
      suggesting that the peptide may exert its effects by activating a guanosine 
      5'-triphosphate (GTP)-binding protein
FAU - Brezina, V
AU  - Brezina V
AD  - Department of Biology, University of California, Los Angeles 90024.
FAU - Eckert, R
AU  - Eckert R
FAU - Erxleben, C
AU  - Erxleben C
LA  - eng
GR  - GM07185/GM/NIGMS NIH HHS/United States
GR  - R01 NS08364/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 0 (Ion Channels)
RN  - 0 (Nerve Tissue Proteins)
RN  - 0 (Neuropeptides)
RN  - 0 (Thionucleotides)
RN  - 37589-80-3 (Guanosine 5'-O-(3-Thiotriphosphate))
RN  - 58569-55-4 (Enkephalin, Methionine)
RN  - 64190-70-1 (FMRFamide)
RN  - 78761-61-2 (enkephalin-Met, Arg(6)-PheNH2(7)-)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - E0399OZS9N (Cyclic AMP)
RN  - RWP5GA015D (Potassium)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Action Potentials/drug effects
MH  - Animals
MH  - Aplysia
MH  - Calcium/*physiology
MH  - Cyclic AMP/pharmacology
MH  - Enkephalin, Methionine/analogs & derivatives/pharmacology
MH  - FMRFamide
MH  - Ganglia, Sympathetic/physiology
MH  - Guanosine 5'-O-(3-Thiotriphosphate)
MH  - Guanosine Triphosphate/analogs & derivatives/pharmacology
MH  - In Vitro Techniques
MH  - Ion Channels/*physiology
MH  - Nerve Tissue Proteins/pharmacology
MH  - Neurons/*physiology
MH  - Neuropeptides/pharmacology/*physiology
MH  - Potassium/physiology
MH  - Temperature
MH  - Thionucleotides/pharmacology
PMC - PMC1192566
EDAT- 1987/07/01 00:00
MHDA- 1987/07/01 00:01
PMCR- 1987/07/01
CRDT- 1987/07/01 00:00
PHST- 1987/07/01 00:00 [pubmed]
PHST- 1987/07/01 00:01 [medline]
PHST- 1987/07/01 00:00 [entrez]
PHST- 1987/07/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1987.sp016632 [doi]
PST - ppublish
SO  - J Physiol. 1987 Jul;388:565-95. doi: 10.1113/jphysiol.1987.sp016632.