Bronchoalveolar Lavage Cell and Mediator Responses to Hyperpnea-induced Bronchoconstriction in the Guinea Pig

Abstract

Abstract We studied the association between bronchoconstriction and bronchoalveolar lavage (BAL) cell and mediator profiles in unsensitized guinea pigs (GP) after hyperpnea to determine whether eicosanoids or histamine are released during hyperpnea-induced bronchoconstriction (HIB). Twelve animals were challenged with warm, moist (WM) air (T = 35° C, relative humidity = 91 to 94%), 14 with room dry (RD) air (T = 25° C, relative humidity < 2.1%), and 18 with cold, dry (CD) air (T = 7° C, relative humidity < 2.1%). Lung resistance (Rl) and elastance (El) were recorded at baseline and at 2-min intervals after hyperventilation. Challenges were terminated either when a ⩾ 100% increase in Rl was observed postchallenge or after completion of a 135 breaths/min challenge if Rl did not increase. BAL was performed, and samples were analyzed for total cells, white cell and epithelial cell differentials, total protein concentration, and mediator content. Results showed: (1) significant posthyperpnea increases in Rl and El in RD and CD animals, but not in WM animals; (2) no significant differences in BAL total cells, percentage of red blood cells, or white blood cell differentials between the three groups; (3) significantly higher percentages of epithelial cells in BAL fluid of RD and CD animals when compared with those in WM animals; (4) significantly more immunoreactive prostaglandin D2 (PGD2), F2α (PGF2α), thromboxane B2 (TxB2), and leukotriene B4 (LTB4), but not leukotrienes C4, D4, E4 (SRSA), total protein, or histamine in BAL from WD and CD animals when compared with WM animals; (5) significant positive, linear correlations between BAL levels of PGD2, PGF2α, TxB2, and LTB4 and magnitude of posthyperpnea Rl and El. Our results show that prostanoids and LTB4 are released coincident with and in proportion to the magnitude of this response.