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Contraction increases the T 2 of muscle in fresh water but not in marine invertebrates
Author(s) -
Meyer Ronald A.,
Prior Barry M.,
Siles Roxana I.,
Wiseman Robert W.
Publication year - 2001
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.702
Subject(s) - scallop , homarus , crayfish , stimulation , adductor muscles , biology , metabolite , contraction (grammar) , anatomy , crustacean , chemistry , fishery , biochemistry , endocrinology
Previous studies suggest that the activity‐induced increase in 1 H‐NMR transverse relaxation time ( T 2 ) observed in mammalian skeletal muscles is related to an osmotic effect of intracellular metabolite accumulation. This hypothesis was tested by comparing T 2 (measured by 1 H‐NMR imaging at 4.7 T) and metabolite changes (measured by 31 P‐NMR spectroscopy) after stimulation in the muscles of a freshwater (crayfish, Orconectes virilis ) vs two osmoconforming marine invertebrates (lobster, Homarus americanus ; scallop, Argopecten concentricus ). Intracellular pH significantly decreased after stimulation in the lobster tail muscle, but not in the crayfish tail or scallop phasic adductor muscles. The decrease in phosphoarginine‐to‐ATP ratio after stimulation was similar in the three muscles. Muscle T 2 increased from 37 to 43 ms ( p < 0.02, n = 7) after stimulation in crayfish, but was unchanged in lobster muscle (32 ms, n = 7), and significantly decreased (from 40 to 36 ms, p < 0.02, n = 11) in scallop muscle. The observation that T 2 does not increase after stimulation in muscles of marine invertebrates with high natural osmolarity is consistent with the hypothesis that the T 2 increase in mammalian muscle is related to osmotically driven shifts of fluid between subcellular compartments. Copyright © 2001 John Wiley & Sons, Ltd.Abbreviations used: P Arg phosphoarginineP i inorganic phosphate