Emeritus Professor of Zoology, Department of Biology
Emeritus Research Professor, Békésy Laboratory of Neurobiology (PBRC)
Harvard University, Ph.D. (Biology)
Harvard Medical School, A.M. (Medical Sciences)
Harvard University, A.B. Cum Laude (Biology)
Cellular control of secretion from neurons and endocrine cells. Ionic currents underlying pacemaking and patterned impulse firing.
The research utilized electrophysiogical techniques, e.g. patch-clamping, to characterize ionic currents of single cells. Fluorescence microscopy with the vital dye fura 2 was used to assess intracellular calcium concentrations. Secretion from single cells under patch clamp was monitored by the increased membrane electrical capacitance which occurs when hormone storage granules fuse with the membrane and open to release their contents. Most recently the release of prolactin, which acts to control blood osmotic pressure in vertebrates, has been characterized using isolated cells of the Tilapia pituitary.
Initially we worked with the neurosecretory system of the crab eyestalk which provided easily isolated, large neurons and secretory terminals large enough to permit the first intracellular recordings from nerve terminals.
An earlier project exploited the 9-neuron cardiac ganglion of lobsters and crabs that commands the rhythmic contractions of these neurogenic hearts. Each of the neurons was found to be capable of generating the rhythmic bursts of action potentials which act on other cells of the ganglion and on heart muscle cells. The electrically controlled ionic currents were characterized by voltage- and space clamping of the neurons isolated by ligatures.
Cooke, I.M. (2002) Reliable, responsive pacemaking and pattern generation with minimal cell numbers: the crustacean cardiac ganglion. Biol. Bull. 202:108-136
Stuenkel, E.L., and I.M. Cooke (1988) Electrophysiological characteristics of peptidergic nerve terminals correlated with secretion. In: D. Ganten and D. Pfaff (Eds.), Current Topics in Neuroendocrinology. (Heidelberg, Springer-Verlag), Vol. 9, pp. 123-150.
Richmond, J.E., R. Penner, R. Keller, and I.M. Cooke (1996) Characterization of the Ca2+ current in isolated terminals of crustacean peptidergic neurons. J. Exp. Biol., 199: 2053-2059.
Seale, A.P., N.H. Richman III, T. Hirano, I.M. Cooke, and E.G. Grau (2003) Cell volume increase and extracellular Ca2+ are needed for hyposmotically induced prolactin release in tilapia. Am. J. Physiol., 284: C1280-C1289.
Xu, S.-H., T. Shimahara, and I.M. Cooke (2011) Capacitance increases of dissociated tilapia prolactin cells in response to hyposmotic and depolarizing stimuli. Gen. Comp. Endocrinol,173:38-47.