ISSN:
1432-2013
Keywords:
Pancreatic islets
;
Na+−K+
;
Ouabain
;
Veratridine
;
Glucose
;
Insulin
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effect of glucose upon the handling of22Na+ by pancreatic islets was investigated. Using a triple-isotope technique, the apparent concentration of Na+ in islet cells was estimated at 50–75 mM. The pattern of22Na+ efflux from perifused islets indicates that this intracellular Na+ load is compartmentalized among a small, possibly organelle-bound pool characterized by a low fractional turnover rate (5%/min) and a large, presumably cystosolic pool displaying a much higher fractional turnover rate (20–34%/min). Glucose provokes a rapid, pronounced and sustained increase in the fractional outflow rate of Na+ across the plasma membrane and, under steady-state conditions, moderately reduces the concentration of Na+ inside the islet cells. The glucose-induced increase in Na+ outflow rate, which is also observed in response to glyceraldehyde and does not require the presence of extracellular Ca2+, might be mediated, in part at least, by an ouabain-resistant ionophoretic system. The experimental data suggest that glucose also increases the inward transport of Na+ in islet cells by a veratridine-sensitive channel.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00584244
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