A comparison of mediator and catecholamine release between exercise- and hypertonic saline-induced asthma

Serum neutrophil chemotactic activity (NCA) and plasma histamine concentrations were measured in 9 asthmatic subjects with exercise-induced asthma after inhalation challenge with ultrasonically nebulized 3.6% hypertonic saline, which was administered either in a dose-dependent manner (HSDR) or as a continuous single dose (HSC), and after cycle ergometer exercise. The mean decreases in FEV1 elicited by HSDR, HSC, and exercise were 26, 27, and 25%, respectively, and were not significantly different. There was an approximate 300% maximal increase in NCA detected after both HSC and exercise challenges. Gel filtration chromatography on columns of Ultragel ACA 34 indicated that the NCA released after HSC provocation and exercise were 600 to 700 kDa. There was an approximate 100% maximal increase in NCA after HSDR challenge, and this was significantly less (p = 0.016) than that after HSC and exercise. Exercise but not hypertonic challenge was associated with a basophilia and a significant increase in plasma histamine. There was a significant increase in plasma norepinephrine concentrations after exercise but not after HSC challenge in 7 asthmatics. Epinephrine concentrations did not change after exercise or HSC inhalation. NCA was measured in 5 subjects subjected to 2 HSC challenges that were separated by 60 min. There was an increase in NCA detected after both provocations. The increase after the second challenge was significantly greater (p = 0.27 x 10(-4)) than that observed after the initial provocation, despite a substantially reduced bronchoconstrictor response after the second challenge.