Our aim is to identify, separate and characterize the voltage- and transmitter-activated ionic conductances underlying excitation in identified leech neurons in different species. During the last 10 years we have amassed a substantial amount of information on mechanisms of excitation in several leech neurons. One of the more important findings was that functionally identified neurons differ in their responsiveness to the classical Na- and K- channel blockers. The varying drug-sensitivities occurred in an orderly fashion suggesting that even closely related neurons posses specific sets of ionic conductances and are not identical. However, until the recent introduction in our laboratory of the two electrode voltage-clamp and patch clamp techniques, clear separation or kinetic analysis of ionic currents in leech neurons was completely lacking. There is no information on the properties of either voltage- or chemically activated channels in the leech or other annelids. The work should therefore provide interesting information regarding the phylogenetic evolution of ionic channels. Furthermore, because a large and growing body of information regarding neuronal function and biochemical content is afailable for various leech species, this preparation seems particularly suitable for the study of correlation between a cell's function and the properties of its ionic channels. We hope that findings on the biophysical properties of leech neurons will be not only of interest to the numerous workers who are presently studying leech behavior but will provide information of general significance on phylogenetic evolution of ionic conductances.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS018054-05
Application #
3398110
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1982-03-01
Project End
1989-11-30
Budget Start
1987-12-01
Budget End
1988-11-30
Support Year
5
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Yale University
Department
Type
Schools of Medicine
DUNS #
082359691
City
New Haven
State
CT
Country
United States
Zip Code
06520
Wilson, R J; Kristan Jr, W B; Kleinhaus, A L (1996) An increase in activity of serotonergic Retzius neurones may not be necessary for the consummatory phase of feeding in the leech Hirudo medicinalis. J Exp Biol 199:1405-14
Perruccio, L; Kleinhaus, A L (1996) Anatomical pathways connecting lip sensory structures and central nervous system in hirudinid leeches visualized by carbocyanine dyes and laser scanning confocal microscopy. Invert Neurosci 2:183-8
Kleinhaus, A L; Zeman, R J (1994) Protein phosphatase inhibitors prolong Ca(2+)-transients and divalent cation-dependent action potentials in leech Retzius cells. Brain Res 650:326-30
Johansen, J; Kleinhaus, A L (1990) Ionic conductances in two types of sensory neurons in the leech, Macrobdella decora. Comp Biochem Physiol A Comp Physiol 97:577-82
Acosta-Urquidi, J; Sahley, C L; Kleinhaus, A L (1989) Serotonin differentially modulates two K+ currents in the Retzius cell of the leech. J Exp Biol 145:403-17
Johansen, J; Kleinhaus, A L (1988) Voltage clamp characterization of a calcium-dependent chloride conductance in a putative invertebrate motoneuron. J Comp Physiol A 162:57-65
Yang, J; Johansen, J; Koehm, S et al. (1987) In situ patch-clamp recording of calcium-activated potassium channels from an identified leech neuron. Brain Res 419:324-8
Johansen, J; Yang, J; Kleinhaus, A L (1987) Voltage-clamp analysis of the ionic conductances in a leech neuron with a purely calcium-dependent action potential. J Neurophysiol 58:1468-84
Petroff, O A; Hogan, E; Johansen, J et al. (1987) Proton magnetic resonance spectroscopy of leech muscle and nervous system. Comp Biochem Physiol B 87:927-31
Johansen, J; Kleinhaus, A L (1987) Saxitoxin differentiates between two types of Na+-dependent potentials in the Retzius cell of hirudinid leeches. J Exp Biol 131:351-63