QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online October 18, 2006
Journal of Experimental Biology 209, 4313-4318 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02523

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Uriona, T. J. Articles by Farmer, C. G. Search for Related Content PubMed PubMed Citation Articles by Uriona, T. J. Articles by Farmer, C. G.

Contribution of the diaphragmaticus muscle to vital capacity in fasting and post-prandial American alligators (Alligator mississippiensis)

T. J. Uriona^* and C. G. Farmer

Department of Biology, 257 South 1400 East, University of Utah, Salt Lake City, UT 84112, USA

^* Author for correspondence (e-mail: uriona{at}biology.utah.eu)

Accepted 5 September 2006

The importance of the diaphragmaticus muscle to vital capacity was investigated in juvenile American alligators by transection of this muscle. In both fasting and post-prandial animals a pneumotach was used to study vital capacity that was stimulated by either a hypercapnic-anoxic gas mixture or a hypercapnic-normoxic gas mixture in two types of control groups of animals (a shamoperated group and a group receiving no treatment) and in the experimental (transected) group. Transection did not significantly reduce vital capacity or affect time of inspiration or expiration in fasted animals. For both the experimental and control groups vital capacity was greatly reduced in post-prandial animals compared to the fasting state. Furthermore, alligators with a transected diaphragmaticus muscle showed a 16-18% greater drop in vital capacity in the post-prandial state than did alligators with an intact diaphragmaticus muscle. The post-prandial decrease in vital capacity for alligators with a transected diaphragmaticus occurred concomitantly with a significant increase in time to inspire and a decrease in maximum rate of inspiration when compared to control animals. The results from this study suggest that the diaphragmaticus muscle plays an important role in enabling large volumes of oxygen to be taken into the lungs in the post-prandial state.

Key words: alligator, Alligator mississippiensis, CO₂ breathing, diaphragmaticus, ventilation, post-prandial state, vital capacity, evolution, archosaur, ventilatory mechanics, crocodilian