Avtor/Urednik		Pangršič, Tina
Naslov		Elektrofiziološke lastnosti podganjih astrocitov v celični kulturi
Tip		monografija
Kraj izdaje		Ljubljana
Založnik		Univerza v Ljubljani, Medicinska fakulteta
Leto izdaje		2006
Obseg		str. 63
Jezik		slo
Abstrakt		It was shown that astrocytes secrete glutamate in response to chemical stimuli and to swelling, which may modulate neuronal activity. Recent observations suggest an exocytotic release pathway, however direct evidence has not been provided. Exocytosis is reflecting in membrane surface area changes. To monitor them we used a whole-cell patch clamp set-up and measured cell capacitance, a parameter, linearly proportional to the membrane surface area. Glutamate release was measured by enzymatic assay. In the presence of glutamate NAD+ is reduced to fluorescent NADH, therefore glutamate secretion is detected as an increase in NADH fluorescence. Following the addition of a chemical messenger, which triggers an increase in the [Ca2+]i, we observed simultaneous increases in capacitance and NADH fluorescence. This is consistent with the view that in astrocytes regulated exocytosis mediates the release of glutamate. Next, we investigated to what extent astrocytes swell in response to chemical messengers and whether hypoosmotic solution activates the process of regulated exocytosis. Swelling was measured by monitoring time-dependent changes in the cell cross-section area. The application of chemical messengers, which trigger an increase in [Ca2+]i, resulted in no swelling. It is concluded that chemical messenger-induced glutamate release is not associated with cell swelling. Further more, simultaneous measurements of swelling, membrane currents (conductance) and capacitance demonstrated that exposure of cells to hypoosmotic medium (210 mOsm for 200 s) results in astrocyte swelling by an average of 40%, in an increase in membrane currents, but however, without any corresponding change in membrane capacitance. Since we demonstrated that the capacitance measurements have the sensitivity to detect increases in cell surface area as small as 0. (Abstract truncated at 2000 characters)
Deskriptorji		ASTROCYTES CELLS, CULTURED CYCLOLEUCINE GLUTAMATES CALCIUM RATS, WISTAR EXOCYTOSIS ELECTRIC CONDUCTIVITY RECEPTORS, GLUTAMATE PATCH-CLAMP TECHNIQUES