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PREDICTIVE STUDIES VI (PS VI): Extension of O2 Tolerance by Intermittent Exposure
Major Category: Extension of O2 tolerance in animals (PS VI)

Expt. Title: Optimization of tolerance to intermittent O2 exposure in rats at 1.5, 2.0, and 4.0 ATA. (Expt. 9.71a) (Component of Predictive Studies VI)

Date: 1988-1989

Description:

To determine rates of recovery from different degrees of O2 poisoning, O2 exposure periods of 20, 60, or 120 minutes were systematically alternated with a constant normoxic interval whose duration was also varied systematically from 5 to 180 minutes in different exposures. Durations of normoxic intervals were selected to provide the same hyperoxic: normoxic ratios for each of the three O2 exposure periods. This was done to determine whether the toxic events accumulated over a relatively long O2 exposure (120 minutes) reversed on return to normoxia at the same rate as those that accumulated during shorter O2 exposures (60 or 20 minutes).

Durations of the O2 periods and normoxic intervals for intermittent exposure patterns that have been studied at 1.5, 2.0, and 4.0 ATA are shown in the table below.

 

TABLE: Intermittent O2 Exposure Patterns Tested to Optimize O2 Tolerance Extension in Rats
O2 EXPOSURE		NORMOXIC INTERVAL (MIN)
ATA	MIN	5	10	15	20	30	60	120	180
	20	X	X		X
4.0	60			X		X	X		X
	120					X	X	X
	20	X	X		X
2.0	60			X		X	X		X
	120					X	X	X
	20	X	X
1.5	60			X		X	X
	120					X	X	X

MEASUREMENTS:  Survival time, convulsion time, body weight, wet and dry lung weights. Data contained in report.

REPORT: Clark, J.M., and C.J. Lambertsen. Principles of O2 tolerance extension defined in the rat by intermittent O2 exposure at 2.0 and 4.0 ATA (ABSTRACT). Undersea Biomed. Res. 16 (Supp.): 99, 1989.

REPORT: Hall, D.A. The Influence of the Systematic Fluctuation of PO2 upon the Nature and Rate of Development of O2 Toxicity in Guinea Pigs. Master’s Thesis in Pharmacology. Philadelphia, PA: Dept. of Pharmacology, University of Pennsylvania, 1967.

07 February 2000 10:26:59 AM