QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 2, 2007
Journal of Experimental Biology 210, 3910-3918 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.009662

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Alpert, M. H. Articles by Sillar, K. T. Search for Related Content PubMed PubMed Citation Articles by Alpert, M. H. Articles by Sillar, K. T.

Nitric oxide modulation of the electrically excitable skin of Xenopus laevis frog tadpoles

Michael H. Alpert, HongYan Zhang, Micol Molinari, William J. Heitler and Keith T. Sillar^*

School of Biology, University of St Andrews, St Andrews, Fife, KY16 9TS, UK

View larger version (12K): [in this window] [in a new window]   Fig. 1. (A) Schematic diagram of the preparation used to initiate and monitor skin impulses in stage 37/38 Xenopus embryos. SKC (sharp), sharp microelectrode for intracellular recording from skin cells; SKC (patch), patch microelectrode for intracellular recording from skin cells; SKC (ext), extracellular recording suction electrode on skin; Stim (ext), extracellular stimulating suction electrode on skin; VR (ext), extracellular recording suction electrode on ventral root; YS, yolk sac. Scale bar, 1 mm. (B) Intracellular recording from a skin cell with a sharp microelectrode (lower trace) reveals a long duration impulse that is approximately coincident with a multi-phasic impulse recorded extracellularly from a nearby patch of skin (upper trace). (C) Intracellular recording with a patch microelectrode (lower trace) reveals a skin impulse with a similar shape to that recorded with a sharp microelectrode, except that the rising phase is faster. The same stimulus that initiates a skin impulse initiates swimming monitored by an extracellular recording from the ventral root (upper trace). (B,C) The broken horizontal line is set at 0 mV. The asterisk indicates the time of the stimulus.

View larger version (15K): [in this window] [in a new window]   Fig. 2. The effects of the NO donor SNAP on skin cell electrophysiology. (A) Sequential measurements from a patch recording of a single skin cell, which was maintained throughout the experiment. SNAP (horizontal line) reversibly increases the impulse duration (Ai) and the delay from stimulus (Aii, but note that there is an initial decrease in delay; down arrow) and decreases the resting membrane potential (Aiii). Control (pre-application) data are shown as blue diamonds, SNAP data are magenta squares, and wash data are green triangles. (B) Individual responses to stimuli applied at times indicated by the up arrows above the time axis in (A). The resting membrane potential is shown at the start of each record. The records are aligned at the time of the stimulus, and the vertical broken line indicates the response delay in control conditions. Times to peak of skin impulses were 11.3 ms in control (Bi), 13.6 ms in SNAP (Bii) and 12.6 ms in wash (Biii).

View larger version (8K): [in this window] [in a new window]   Fig. 3. (A) Pooled data from 27 preparations showing SNAP effects on skin cell impulse duration (A) and delay from stimulus (B) and skin cell resting potential (C). In each preparation measurements of each parameter were taken with sharp microelectrodes from at least 8 different skin cells in control (blue diamond), SNAP (magenta square) and wash (green triangle) conditions. Single representative values for each parameter in each condition were obtained from each preparation as the average of the duration and resting potential measurements, and the least-squares regression slope of the delay measurements. Values are means ± s.e.m. of these representative values.

View larger version (18K): [in this window] [in a new window]   Fig. 4. CPTIO reverses the effects on SNAP. (A) Data from a single preparation in which measurements of skin impulse duration (Ai) and delay from stimulus (Aii) and skin cell resting potential (Aiii) were taken with sharp microelectrodes from different skin cells in control (blue diamond), SNAP (magenta square) and SNAP+CPTIO (green triangle) conditions. (B) Pooled data from nine preparations, with analysis similar to that of Fig. 3.

View larger version (71K): [in this window] [in a new window]   Fig. 5. Location of NOS and NO production in Xenopus embryo skin. (A) Bright-field image of skin surface of wild-type embryo showing general topography of skin cells, some of which are pigmented. Small white spheres are yolk platelets. (B) Punctate pattern of NADPH-diaphorase labelling in wild-type skin cells (blue label). Note diffuse background pigmentation (darker, grey). (C) Similar pattern of NADPH-diaphorase labelling in skin of albino embryo, which lacks pigmentation. (D) nNOS immunofluorescence labels a similar proportion of skin cells. (E) Example of control nNOS experiment in which the primary antibody was omitted and no labeled cells were detectable. (F) DAF2 marks cells producing NO, with similar distribution in skin. White arrows indicate examples of strongly labeled cells (in B, C, D and F). Scale bars, 50 µm. See text and Materials and methods for further details.