Figure 4.

Studies on desensitization of the relaxant responses of PGF_2α (3 μM)-precontracted porcine pulmonary arteries to cathepsin G and thrombin. After the first relaxant response to one enzyme (Exposure I), the porcine pulmonary vessels were exposed to a second challenge (Exposure II) by the same or another enzyme (about 25–35 min later). Columns are mean values and vertical bars represent the standard error of the mean for the number of tissues indicated in parentheses. ^*P<0.05 compared with thrombin (Exposure I).