Question:

c-Src kinase has been reported to be involved in the signalling mechanism of 5-HT-induced vasoconstriction by affecting calcium sensitivity. However, whether c-Src is involved in 5-HT-induced changes in intracellular calcium is unknown. Therefore, the hypothesis was tested that c-Src contributes to 5-HT-induced vasoconstriction by affecting intracellular calcium changes in rat small skeletal muscle arteries.

Methods:

We performed isometric and isobaric myography and FURA-2 fluorimetry on Gracilis arteries of Wistar rats.

Results:

Inhibition of c-Src kinase with 10 µM PP2 in pressurized Gracilis muscle arteries resulted in almost complete inhibition of dose response curve (DRC) to 5-HT (n=7, p<0,05). In contrast, incubation with 10 µM PP3, an inactive analogue of PP2, had no effect on the DRC of 5-HT (n=6, p=0,13). Under isometric conditions, the DRC of the vessels to 5-HT was significant stronger compared to the response in presence of 10 µM PP2 (n=7, p<0,05). Removal of the endothelium did not alter vessel contractile function (n=6, p=0,53) or the influence of the inhibitor of c-Src kinase (n=6, p=0,34). Measurement of intracellular calcium concentration showed that PP2-mediated inhibition of 5-HT-induced DRC was associated with decrease in [Ca(2+)] (n=6, p<0,05).

Conclusion:

The results highlight that c-Src activation is a powerful mechanism to produce vasoconstriction of small skeletal muscle arteries of rats. The effect of c-Src is independent of the endothelium that suggests the functional localisation of the kinase in smooth muscle cells and mediated by an alteration of intracellular calcium.