ISSN:
1432-1424
Keywords:
Ca2+ oscillations
;
Ca2+ wave
;
sarcoplasmic reticulum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Intracellular calcium [Ca2+] i measurements in cell suspension of gastrointestinal myocytes have suggested a single [Ca2+] i transient followed by a steady-state increase as the characteristic [Ca2+] i response of these cells. In the present study, we used digital video imaging techniques in freshly dispersed myocytes from the rabbit colon, to characterize the spatiotemporal pattern of the [Ca2+] i signal in single cells. The distribution of [Ca2+] i in resting and stimulated cells was nonhomogeneous, with gradients of high [Ca2+] i present in the subplasmalemmal space and in one cell pole. [Ca2+] i gradients within these regions were not constant but showed temporal changes in the form of [Ca2+] i oscillations and spatial changes in the form of [Ca2+] i waves. [Ca2+] i oscillations in unstimulated cells (n = 60) were independent of extracellular [Ca2+] and had a mean frequency of 12.6 +1.1 oscillations per min. The baseline [Ca2+], was 171 ± 13 nm and the mean oscillation amplitude was 194 ± 12 nm. Generation of [Ca2+] i waves was also independent of influx of extracellular Ca2+. [Ca2+] i waves originated in one cell pole and were visualized as propagation mostly along the subplasmalemmal space or occasionally throughout the cytoplasm. The mean velocity was 23 +3 μm per sec (n = 6). Increases of [Ca2+] i induced by different agonists were encoded into changes of baseline [Ca2+] i and the amplitude of oscillations, but not into their frequency. The observed spatiotemporal pattern of [Ca2+] i regulation may be the underlying mechanism for slow wave generation and propagation in this tissue. These findings are consistent with a [Ca2+] i regulation whereby cell regulators modulate the spatiotemporal pattern of intracellularly generated [Ca2+] i oscillations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00233351
