Fig. 4.

Effect of P2 receptor blockade on the afferent arteriolar autoregulatory response induced by an increase in perfusion pressure. Pressure-mediated afferent arteriolar autoregulatory responses are depicted before and during P2 receptor blockade with NF-279 (top panel), PPADS (centre panel) and suramin (bottom panel). Autoregulatory responses were induced by increasing perfusion pressure in 30 mmHg increments at 5-min intervals. The data are expressed as a percentage of the control diameter and each data point represents the average diameter response over the last 2 min of each period. Control responses are shown by the black symbols and the response during P2 receptor blockade are shown by the grey symbols. At the end of each protocol, perfusion pressure was returned to 100 mmHg to determine recovery for the pressure stimulus. Data are modified from earlier reports [33, 51]