Effects of non-haemorrhagic injury on the cardiovascular response to tilting in the rat.

In the unanaesthetized uninjured rat a head-up tilt elicited a pressor response, the magnitude of which was directly related to the angle of tilt. The pressor response was reduced by a 4 h period of bilateral hind-limb ischaemia and by a non-fatal scald, although the slope of the regression line relating percentage rise in mean arterial blood pressure to the angle of tilt was unaltered. The degree of impairment of the response was directly related to the severity of the injury. In the uninjured rat there was a sigmoid relationship between the angle of tilt and the mean heart rate during the tilt. No relationship could be demonstrated between angle of tilt and heart rate in the injured rats.