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 PhD Harvard (Biology), 1962 Professor, Department of Zoology Researcher, Békésy Laboratory of Neurobiology Pacific Biomedical Research Center (PBRC) 1993 East-West Road Honolulu, HI 96822 phone: 956-6776 fax: 956-6984 ian@pbrc.hawaii.edu www.pbrc.hawaii.edu/faculty/ian |
 
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Interests Cellular mechanisms linking electrical and secretory activities of peptide-secretory cells, especially the role of calcium movements in control of secretion. Currently, the laboratory is using whole-cell and perforated patch-clamping techniques together with measurements of cell membrane capacitance, to characterize the ionic currents, particularly Ca2+, in relation to exocytotic secretion of prolactin from pituitary cells. The cells are dissociated from a species of fish having the capability of adapting to a wide range of salinities, the tilapia Oreochromis mossambicus. Prolactin functions in adaptation to hypoosmotic conditions and is released in direct response to reduction of medium osmolality. Further, in this species, the prolactin-secreting cells are segregated to a visually distinct lobe of the pituitary, facilitating their isolation. Imaged microfluorimetry with indicator vital dyes such as fura-2AM is being used to follow changes of cytoplasmic Ca2+ in these cells in response to hypoosmotic stimulation. Earlier work exploited the large neurosecretory terminals of the crab X-organ - sinus gland to obtain the first intracellular recordings from secretory terminals; these revealed regenerative Ca2+-mediated impulses and spike broadening during repetitive activity. Patch-clamping of the crab secretory neurons in defined primary culture characterized voltage-gated Ca2+-channels of the somata and the terminals. The technique of isolating and recording from secretory terminals was later extended to mammalian neurohypophyseal terminals in other laboratories. Still earlier work characterized the ionic currents giving rise to burst-forming potentials in lobster cardiac ganglion motorneurons. Intrinsic bursting is also a characteristic of many secretory cells. We found similar currents to those of the cardiac ganglion neurons responsible for bursting in crab secretory neurons and cultured rat vasopressin neurons. [return to top] Richmond, J.E., A. Codignola, I.M. Cooke, and E. Sher, (1996) Calicum-
and barium-dependent secretion from the rat insulinoma cell line
RINm5F: evidence from capacitance tracking and serotonin release.
Pflügers' Arch., 432: 258-269. [return to top] Cooke, I.M. (1999) Physiology of mature crustacean neurosecretory
neurons in culture. In: L.W. Haynes (Ed.), The Neuron in Tissue
Culture. (New York, Wiley & Sons), Ch. 18, pp. 261-277. [return to top] Duan, S., and I.M. Cooke (1997) La3+ selectively inhibits transient
K+ current (IA) of crab peptide secretory neurons. J. Gen. Physiol.,
110(1): 44a. [return to top] Sher, E., A. Codignola, M. Rogers and J. Richmond (1996) Noradrenaline inhibition of Ca2+ channels and secretion in single patch-clamped insulinoma cells. FEBS Lett. 385: 176-180. [return to top] NIH NS15453-09 to -12, Electrical activity and neurosecretion in
vitro, 7/1/92 - 12/31/98, $365,466 (direct costs). |
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