To investigate the biochemical and cellular basis for the rise in polymorphonuclear leukocyte (PMN) count during epinephrine administration, PMN from subjects receiving epinephrine were studied for their capacity to adhere to nylon wool fibers and endothelial cell monolayers. After administration of epinephrine, the PMN count increased by 80% at 5 min, and isolated PMN adherence to nylon fibers fell from a base line of 44±2-18±3%. In contrast, when subjects were infused with the β-antagonist propanolol before receiving epinephrine, the PMN count failed to rise and PMN adherence was normal. Exposure of PMN endothelial cell monolayers to 0.1 μM epinephrine led to diminished PMN adherence that could be blocked by 10 μM propanolol but not by 10 μM phentolamine. Sera obtained from subjects 5 min after receiving epinephrine or from supernates derived from endothelial cell monolayers exposed to 90 nM epinephrine inhibited PMN adherence to nylon fibers. Addition of anticyclic AMP antisera but not anticyclic guanosine monophosphate antisera to the postepinephrine sera or to the postepinephrine supernate derived from the endothelial cell monolayers abolished their inhibitory effect of PMN adherence to nylon fibers. In contrast, direct exposure of PMN to epinephrine failed to affect their adherent properties. Because it has been previously shown that endothelial cells contain β-receptors and respond to catecholamines by raising their intracellular concentrations of cyclic AMP, and that PMN adherence is attenuated by cyclic AMP, it would appear that diminished PMN adherence after epinephrine administration is mediated through endothelial cell β-receptor activity, which in turn impairs PMN margination in vivo and could account for the rise in circulating PMN.
Laurence A. Boxer, John M. Allen, Robert L. Baehner, Vicktoria Amick