Cl Transmembrane signalling and transduction P-Cl-14

P-Cl-13 REGULATORY ROLE OF TIIE MEMBRANE POTENTIAL ON THE ACTIVATION MECHANISM OF SPERM Terez Mgrifin’, Zoldn Krasznai2, Hiroko Izumi3,

THE HYPOTHESIS OF ELECTRONIC CHANNELS ACROSS CELL MEMBRANE YE YUAN-JIEt$,,JIANG YAN’F, LADIK JANOS$. tDepartment of Protein Engineering, Institute of Biophysics, Chinese Academy of Sciences, 1.5Datun

Lajos Tr6n’ and Masaaki Morisawa3 ‘Positron Emission Tomograph Centre and *Department of Biophysics, University Medical School of Debrecen, Hungary and ‘Misaki Marine Biological Station, University of Tokyo. Purpose: Studying sperm activation mechanism. Methods: Experiments were carried out on Cyprinus carpio (vertebrates) and Ciona intestinalis (invertebrates) sperm, using spectrofluorimeter and flow cytometer. Results: Hypoosmotic shock induces structural and permeability changes in the plasma membrane of carp. The permeabilization is coincident in time with the termination of the active motion. Hypoosmotic shock provokes alkalinization (0.15 pH units) in pHi. Carp spermatozoa are remarkably depolarized in the seminal plasma ([K,]=60*8mM, &]=87*16mM) and hypoosmotic activation is accompanied by hyperpolarization. The activation can be reversibly inhibited by potassium channel blockers. Although the sperm activation and chemotaxis of ascidians are completely different from that of the teleosts (Morisawa 1994, Zoological Sci. 11:647) we observed, that extracellular potassium (more than 40 mM) terminated the motility of the activated ciona sperm. Potassium channel blocker 4-AP partially inhibited ciona sperm motility. This work was partially supported by OTKA grants 6184,13974 and JSPSIRc3/96701.

Road, Chaoyang District, Beijing 100101, China SInstitute of Theoretical Chemistry and Laboratory of the National Foundation for Cancer Research, FriedrichAlexander University Erlangen-Niirnberg. Egerlandstrasse 3, D-91058 Erlangen, Germany The

hypothesis of electronic channel across cell be discussed in detail on the basis of the results of quantum chemical calculations on two different kinds of insulin and experimental results in the literature. The hopping mechanism of electron transport in protein molecules will be briefly described. The electron transport pathways in native proteins will be discussed on the basis of the results obtained for different kinds of native proteins. The biological meaning of a.c. conductivity in native proteins in high frequency range will be clearly explained. The possible existence of electronic channels across cell membrane to transport biological signals between both sides of the cell membrane will be presented in detail. The further conclusion is that electronic channels could not only transport signals but also act as bridges to couple the oxidation-reduction reactions between the both sides of cell membrane. Finally, two experiments are suggested for the further verification of this hypothesis.

membrane will

P-Cl-15 ELECTRICAL BURSTING AND LUMINAL CALCIUM OSCILLATION IN PANCREATIC P-CELL MODEL

P-Cl-16 SINGLE MUTATION CONVERTS RIIODOIWN INTO CONE VISUAL PIGMENT IMAI H, KOJIMA D, OURA T. TERAKlTA A, SHICHIDA Y. Dept. of Biophys., Fat. of Sci., Kyoto Univ. (J)

CHAY, TR. Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (USA)

Purpose: The goal is to explain how the ion channels, the receptors embedded in the plasma membrane, and the endoplasmic reticulum in pancreatic p-cells interact so as to generate electrical bursting and the oscillation in the intracellular calcium concentrafion. [Ca2+]i. Methods: The Chay bursting model (Chay TR, 1990, Am. J. Physiol. 258: CSS-C965) is extended to include the dynamic changes of the calcium concentration in the lumen of the endoplasmic reticulum, [Caz+]iurn. Results: It is shown that electrical bursting and the [Cal+]i oscillation are driven by a slow oscillation of [Ca2+llum. The present model uniquely provides answers to some puzzling phenomena; e.g., (i) Why do isolated single cells

Purpose: Most vertebrates have two types of photoreceptor cells, rods and cones, which mediate twilight and daylight vision, respectively (Visual Duplicity). In order to determine the molecular mechanismsgenerating the difference in phororesponsebetween the photoreceptor cells, we investigated molecular properties of visual pigments and their site-directed mutants. Methods: Thermal decay rate of physiologically active meta H-intermediate and a regeneration rate of pigment were observed with timeresolved low temperature spectroscopy. Results: In relation to the less photosensitivity

and faster adaptation of cones than rods, cone visual pigments display faster decay of meta II and faster regeneration than the rod pigment rhodopsin. Furthermore, single replacement of

burst with a low frequency while intact b-cells

in an islet burst with a much higher frequency? (ii) Why do p-cells in the islet exhibit a biphasic responsewhen glucoseis added in the medium? Conclusions: Verification of the model prediction that [Ca2+llumis a primary oscillator which drives electrical bursting and [Caz+]i oscillation awaits experimental testing. Experiments using fluorescent dyes such as mag-fura 2 or aquorine could provide relevant information.

glutamate at the position 122 of rhodopsin

generated a pigment whose properties are similar to those of cone pigments. Conclusions: The amino acid residue positioned at 122 is a determinant of the

molecular properties of rod and cone pigments, which would be one of the molecular basisof visual duplicity. 90

Serum anticholinergic activity: a possible peripheral marker of the anticholinergic burden in the central nervous system in Alzheimer's disease.

We review the utility of serum anticholinergic activity (SAA) as a peripheral marker of anticholinergic activity (AA) in the central nervous system (C...
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