Insulin/igf-1 binding ratio in skeletal and cardiac muscles of
vertebrates: a phylogenetic approach .
P[acute]arrizas, Marcelina, Miguel A. Maestro, Nuria Ba[tilde]nos,
Isabel Navarro, Jos[acute]e Planas, and Joaquim Guti[acute]errez.
Departament de Fisiologia, Facultat de Biologia, Universitat de
Barcelona, Barcelona 08028, Spain
APStracts 2:0168R, 1995.
Insulin and IGF-1 receptor binding and tyrosine kinase activity were
characterized in cardiac and skeletal muscles of several vertebrates.
Specific insulin binding per unit weight of skeletal muscle was
clearly higher in pigeon and rat than in ectothermic vertebrates (32
+/- 5 % and 25 +/- 2.7 %/100 mg initial tissue in pigeon and rat
respectively, versus 4.4 +/- 0.2 %/100 mg in carp samples). Insulin
binding clearly predominated over IGF-1 binding in skeletal muscle of
endotherms (IGF-1 binding was 7.7 +/- 0.5 %/100 mg in rat). In
ectothermic vertebrates the situation was reversed, and IGF-1 binding
was higher than insulin binding. In cardiac muscle, specific binding
of both insulin and especially IGF-1 were higher than the values
found in skeletal muscle of the same species (IGF-1 binding was 60
+/- 4, 103 +/- 2 and 20 +/- 3 %/100 mg in carp, turtle and rat). The
tyrosine kinase activity of insulin and IGF-1 receptors of all
species studied presented basal phosphotransferase rates (250-1600
fmol P/[mu]g protein/30 min) and percentage of stimulation (150-520
%) with clear differences between species.The present data suggest
that insulin and IGF-1 binding to skeletal and cardiac muscles change
through the vertebrate scale in both quantity and activity.
Received 26 January 1995; accepted in final form 19 June 1995.
APS Manuscript Number R62-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.