Affordable Access

Publisher Website

Desensitization to norepinephrine includes refractoriness of calcium release in myocardial cells

Authors
Journal
Biochemical and Biophysical Research Communications
0006-291X
Publisher
Elsevier
Publication Date
Volume
151
Issue
1
Identifiers
DOI: 10.1016/0006-291x(88)90598-0
Disciplines
  • Physics

Abstract

Abstract Localization of myoplasmic free calcium was measured in fura2-loaded single rat myocardial cells to determine whether the mechanism of norepinephrine desensitization includes redistribution of calcium. Fluorescence intensities at each pixel were quantitated by use of a photon-counting, microchannel plate camera. From these images, values of calcium-dependent fluorescence intensity averages in whole cells, areas of calcium release (as zones of high inracellular calcium concentrations), and ratios of fluorescence intensity in central vs. peripheral sites were determined. Stimulation by 1 nM norepinephrine caused an increase in total free intracellular calcium and an activation of intracellular calcium release sites from subsarcolemmal pools initially and later from centrally located calcium pools. Subsequent addition of 100 nM norepinephrine failed to cause significant intracellular calcium release from centrally located pools. In contrast, forskolin exposure still released high concentrations of calcium from these central pools. These results indicate that pretreatment with even a relatively small concentration of norepinephrine causes markedly decreased subsequent intracellular calcium release from centrally located sarcoplasmic reticulum because of a refractoriness of the link between receptor activation and calcium release.

There are no comments yet on this publication. Be the first to share your thoughts.

Statistics

Seen <100 times
0 Comments

More articles like this

Desensitization to norepinephrine includes refract...

on Biochemical and Biophysical Re... Feb 29, 1988

Calcium antagonism and norepinephrine release in m...

on Journal of Cardiovascular Phar... 1992

Muscarinic stimulation of calcium influx and norep...

on Journal of Biological Chemistr... Jun 15, 1988

Subcellular localization of calcium release in iso...

on Journal of Cardiovascular Phar... 1991
More articles like this..