Effects of acute ozone exposure on the electrophysiological properties of guinea pig trachea
- Johns Hopkins Medical Institutions, Baltimore, MD (United States)
Acute ozone (O{sub 3}) exposures produce an increase in the apparent permeability of the tracheal epithelium, but the mechanism of this response is poorly understood. Comparison of previous studies suggests that qualitative differences may exist between measurements made in vivo or in vitro. To test this possibility we used both in vitro and in vivo electrophysiological techniques to investigate the effects of O{sub 3} exposure on guinea pig tracheal epithelium. Male Hartley guinea pigs were exposed to either 1 or 2 ppm O{sub 3} or to filtered air for 3 h and were studied 0, 6, or 24 h after exposure. Air-exposed animals had in vitro mean tracheal potential (V{sub T}) -32.0 {+-} 1.5 mV, conductance (G{sub T}{sup L}) 2.18 {+-} 0.22 mS/cm, short-circuit current (I{sub SC}{sup L}) 62.6 {+-} 3.7 {mu}A/cm, and diameter (D) 2.44 {+-} 0.10 mm. In vitro properties after 1 ppm O{sub 3} exposure did not differ at any time point from control. Two parts per million O{sub 3} increased I{sub SC}{sup L}, but only at 6 h postexposure. The effect of O{sub 3} on I{sub SC}{sup L} was abolished by amiloride. There were no significant changes in V{sub T}, G{sub T}{sup L}, or D. In vivo tracheal potential under pentobarbital anesthesia was -19.7 {+-} 1.7 mV. At 6 h postexposure to 2 ppm O{sub 3}, but not at 0 or 24 h, in vivo V{sub I} was increased. Thus, acute exposure of guinea pigs to a high concentration of O{sub 3} caused a delayed increase in Na{sup +} absorption by the trachea with no change in conductance. This indicates that paracellular permeability of guinea pig tracheal epithelium was not substantially increased by acute O{sub 3} and suggests that enhanced macromolecular uptake in this species probably occurs transcellularly. 24 refs., 1 fig., 2 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 81780
- Journal Information:
- Journal of Toxicology and Environmental Health, Vol. 43, Issue 1; Other Information: PBD: 1994
- Country of Publication:
- United States
- Language:
- English
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