Potential Regulatory Role of Inflammatory Cells on Local Vascular Smooth Muscle Tone

A neutrophil-derived relaxing factor (NDRF) from oyster glycogen (OG)-elicited rat PMN, which causes an endothelium independent relaxation of rat aorta, and which is pharmacologically indistinguishable from endothelium-derived relaxing factor (EDRF) has been described. Experiments were designed to evaluate the presence of NDRF in PMN from rat -whole blood, -carrageenan pleurisy, -OG peritonitis, and guinea pig (GP) -OG peritonitis, as well as in OG-elicited rat macrophages (M phi). Significant vascular relaxing activity was found using rat PMN from OG peritonitis and carrageenan pleurisy, as well as from OG-M phi. Little or no activity was found in rat whole blood PMN or PMN from GP-OG peritonitis. These results suggest that NDRF activity may be expressed upon cellular migration to an inflammatory site in the rat, and may not be present in all species. Also, all inflammatory cells examined were capable of reversing EDRF-dependent relaxations when stimulated to produce superoxide anion suggesting a dual regulatory role for these cells on local vascular tone.