Abstract EMVBM 3rd EVBM 2005

J. Vasc. Biol. 42, Sup:2 (2005) p94

P272 Characterisation of the Ca²⁺ signalling in the endothelial cells of the precapilallary arterioles.

L.Borisova, D.Eisner, S.Wray, T.Burdyga

The Physiological Laboratory, University of Liverpool, Liverpool, GB.

Endothelial cells of the pre-capillary arterioles showed spontaneous Ca²⁺ events which ranged from elemental Ca²⁺ events such as Ca²⁺ puffs, intermediate Ca²⁺ events such as Ca²⁺ spikes to full size Ca²⁺ waves. The predominant Ca²⁺ signals in the endothelial cells at rest consisted of localised Ca²⁺ events which had variable amplitude and spatial spread and occurred at several discharging sites. Removal of extracellular Ca²⁺ or addition of nifedipine had no significant effect on Ca²⁺ signalling in endothelial cells at rest. Addition of CPA produced an elevation of the baseline level of [Ca²⁺]_i and complete inhibition of all Ca²⁺ events in the endothelial cells which suggests the pivotal role of Ca²⁺ release from the store(s). In order to further study the mechanisms of Ca²⁺ release from the store(s) in the endothelial cells the effects of ryanodine (a blocker of the RyRs) and 2-APB (a blocker of the IP₃Rs) have been investigated. Ryanodine (10-50 μM) had no effect on the Ca²⁺ events in the endothelial cells. 2-APB (50 μM) completely and reversibly abolished all the Ca²⁺ events in the endothelial cells. Application of carbachol (10 μM) produced regular Ca²⁺ oscillations in the endothelial cells which were resistant to nifedipine, removal of extracellular Ca²⁺, ryanodine and were fully blocked by 2-APB. These data suggest that in endothelial cells of the precapillary arterioles spontaneous and carbachol induced Ca²⁺ events are dependent exclusively on Ca²⁺ release from the store mediated by IP₃Rs.

P272	Characterisation of the Ca²⁺ signalling in the endothelial cells of the precapilallary arterioles.
L.Borisova, D.Eisner, S.Wray, T.Burdyga
The Physiological Laboratory, University of Liverpool, Liverpool, GB.