[abstract] NOVEL MECHANSIMS FOR REDUCED BUBBLE FORMATION IN THE RAT

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[abstract] NOVEL MECHANSIMS FOR REDUCED BUBBLE FORMATION IN THE RAT

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Title: [abstract] NOVEL MECHANSIMS FOR REDUCED BUBBLE FORMATION IN THE RAT
Author: Wislff, U; Brubakk, AO
Abstract: Background: Recently we demonstrated that a single bout of high intensity aerobic exercise 20-hour prior to the dive, protect rats from severe decompression/bubble formation and death. The mechanism behind is not known. Gas nuclei are proposed to exist adhered to blood vessel endothelium, which is strongly controlled by nitric oxide (NO). Aside from effects on vascular tone, NO has physiological properties that may be antiatherogenic, so an increase in NO might reduce the hydrophobicity of the endothelial wall, reducing the number of bubble precursors. A reduction of NO should have the opposite effect. The aim of the present study was to determine the effect of blocking NO synthesis on bubble formation in trained and sedentary rats exposed to hyperbaric pressure. Methods: 32 adult female Sprague-Dawley rats (270-320g) were randomly assigned into training or sedentary control, with and without blockade of NOS, using L-NAME. Trained rats performed aerobic interval training on a treadmill for 1.5h, 20h prior to the dive. Rats were compressed (200kPa/min) to 700kPa, maintained for 45-min breathing air, decompressed (50 kPa/min), anaesthetized and the right ventricle insonated using Doppler ultrasound. The present exercise protocol reduced bubble formation and increased survival in rats weighing more then 300g. As expected from this particular model, rats weighing less than 300g produced few bubbles and survived the protocol. When NOS was blocked the dive protocol induced a lot of bubbles in all sedentary rats with a body weight less than 300g. However, a single bout of training decreased bubble formation substantially and increased survival despite NOS-blockade. Conclusion: The present study demonstrates two previously unreported findings, that administration of L-NAME allows substantial bubble formation and decrease survival in sedentary rats, and that a single bout of exercise protects NO-blocked rats from severe bubble formation and death.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1109
Date: 2002

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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