Journal of Applied Physiology, Vol 76, Issue 3 1150-1155, Copyright © 1994 by American Physiological Society

ARTICLES

Ontogeny of dry gas hyperpnea-induced bronchoconstriction in guinea pigs

T. M. Murphy, D. W. Ray, L. E. Alger, I. J. Phillips, J. C. Roach, A. R. Leff and J. Solway
Department of Pediatrics, University of Chicago 60637.

Adolescent guinea pigs (AGPs) demonstrate dry gas hyperpnea-induced bronchoconstriction (HIB) that shares key features with HIB in humans with asthma. The airways of immature animals exhibit enhanced reactivity to diverse types of stimulation. We tested whether dry gas HIB is also increased in newborn guinea pigs (NGPs). We quantified HIB as the fractional increase of respiratory system resistance (Rrs) over baseline (BL) in five 4- to 7-day-old NGPs after 10 min of hyperpnea, as well as changes in Rrs elicited by intravenous methacholine or capsaicin, and compared these responses with those of AGPs. During hyperpnea, analogous stimuli were delivered by mechanically imposing hyperpnea at 3.0, 4.5, and 6.0 times quiet eucapnic minute ventilation (VE). In AGPs, hyperpnea caused significant bronchoconstriction that increased with VE; peak fractional increase of Rrs was 7.6 +/- 2.0 times BL. In contrast, hyperpnea caused insignificant bronchoconstriction in NGPs (1.4 +/- 0.2 times BL after the largest VE; P < 0.05 vs. AGP). Responses elicited by methacholine (10(-10)-10(-7) mol/kg) or capsaicin (0.01-10.0 microgram/kg) were similar in NGPs and AGPs. In AGPs, hyperpnea suppressed HIB until posthyperpnea. To determine whether the reduced HIB of NGPs was caused by enhanced suppression, NGPs and AGPs were administered acetylcholine (10(-10)-10(-7) mol/kg i.v.) during BL eucapnic ventilation and during eucapnic hyperpnea with warm humidified gas. Responses to acetylcholine were suppressed in AGPs and NGPs to a similar degree. We conclude that HIB is markedly diminished shortly after birth in guinea pigs and that it increases substantially during maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				E. M. Bozanich, T. Z. Janosi, R. A. Collins, C. Thamrin, D. J. Turner, Z. Hantos, and P. D. Sly Methacholine responsiveness in mice from 2 to 8 wk of age J Appl Physiol, August 1, 2007; 103(2): 542 - 546. [Abstract] [Full Text] [PDF]

				B. Chen, G. Liu, F. Shardonofsky, M. Dowell, O. Lakser, R. W. Mitchell, J. J. Fredberg, L. H. Pinto, and J. Solway Tidal breathing pattern differentially antagonizes bronchoconstriction in C57BL/6J vs. A/J mice J Appl Physiol, July 1, 2006; 101(1): 249 - 255. [Abstract] [Full Text] [PDF]

				M. L. Dowell, O. J. Lakser, W. T. Gerthoffer, J. J. Fredberg, G. L. Stelmack, A. J. Halayko, J. Solway, and R. W. Mitchell Latrunculin B increases force fluctuation-induced relengthening of ACh-contracted, isotonically shortened canine tracheal smooth muscle J Appl Physiol, February 1, 2005; 98(2): 489 - 497. [Abstract] [Full Text] [PDF]

				T. D. Mickleborough, R. W. Gotshall, J. Rhodes, A. Tucker, and L. Cordain Elevating dietary salt exacerbates hyperpnea-induced airway obstruction in guinea pigs J Appl Physiol, September 1, 2001; 91(3): 1061 - 1066. [Abstract] [Full Text] [PDF]