Radiation exposure increases vascular responsiveness and leads to arterial hypertension. The goal of the present study was using b-escin skinned rat aorta segments to investigate changes in myofilaments Ca2+-sensitivity in vascular smooth muscle (SM) at hypertension evoked by ionizing radiation and role of protein kinase C (PKC) and Rho-kinase (RhoK) in this process.

On g-irradiated (6 Gy) tissue was shown that the Ca2+-sensitivity of myofilaments had increased. Chelerythrine and staurosporine, PKC inhibitors, normalised radiation-induced changes in Ca2+-sensitivity in SM miofilaments but had no effect on in health tissue. In contrast, the potent RhoK inhibitor HA-1077 was unable to effect on Ca2+-sensitivity in irradiated tissue. PKC activator phorboldibutyrate increased Ca2+-sensitivity in control but was without effects in irradiated vascular tissue. Taken together, this data indicate that irradiation increases the sensitivity of vascular SM myofilaments to Ca2+ and this effect is dependent on PKC but not RhoK activation. This research was supported by a CRDF grant UBI-2452-KV-02.