Faculty Collaboration Database

Histochemical and physiological characteristics of the rat diaphragm. J Appl Physiol (1985) 1985 Apr;58(4):1085-91

Date

04/01/1985

Pubmed ID

3988665

DOI

10.1152/jappl.1985.58.4.1085

Scopus ID

2-s2.0-0021811837 (requires institutional sign-in at Scopus site)   83 Citations

Abstract

The histochemical and contractile characteristics of the adult rat diaphragm were determined. Based on enzyme histochemistry, the rat diaphragm contained 40% type I, 27% type IIa, and 34% type IIb fibers. There were significantly more type I fibers in the ventral costal (VEN) compared with the crural (CRU) region of the muscle and a slightly higher percentage of type I's on the thoracic relative to the abdominal surface. The contractile properties and the effect of temperature (Q10) were similar in the VEN and CRU regions. Increasing temperature produced higher isometric peak tetanic tension, whereas twitch tension, contraction, and one-half relaxation time all decreased. The maximal shortening velocity increased linearly from 22 and 30 degrees C, then plateaued before decreasing between 35 and 37 degrees C. The VEN and CRU force-velocity curves became less concave as temperature increased from 22 to 35 degrees C. Furthermore, the force-frequency relation of both regions was shifted to the right as temperature increased. The isometric and isotonic contractile properties and fiber type distribution are similar in the VEN and CRU regions of the diaphragm. The rat diaphragm is clearly heterogeneous in fiber type distribution and functionally lies intermediate between slow- and fast-twitch limb skeletal muscles.

Author List

Metzger JM, Scheidt KB, Fitts RH

Authors

Robert Fitts PhD Professor in the Biological Sciences department at Marquette University
Karl B. Scheidt MD Associate Professor in the Orthopaedic Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Diaphragm
Female
Histocytochemistry
In Vitro Techniques
Isometric Contraction
Muscle Contraction
Rats
Rats, Inbred Strains
Temperature