Methionine-enkephalin-Arg-Phe immunoreactivity in heart tissue

Methionine-enkephalin-Arg-Phe immunoreactivity in heart tissue Previous findings of enkephalins in cardiac tissue led us to investigate enkephalin distribution in animal models used for cardiovascular research. Canine cardiac methionine-enkephalin (ME) concentrations are low and evenly distributed between atria (4.2 ± 0.6 fmol/mg protein, n = 30) and ventricles (4.4 ± 0.5). In contrast, methionine-enkephalyl-arginyl-phenylalanine (MEAP) immunoreactivity (IR) is higher and preferentially concentrated in the ventricle (112 ± 12) vs. the atria (23.2 ± 2.6 fmol/mg protein). HPLC analysis suggests the atrial/ventricular difference is partly due to altered posttranslational processing. Nearly 90% of ventricular IR is comprised of MEAP (46%) and peptide B (40%) whereas these peptides represent less than half of the atrial content. A nonneuronal localization is indicated because the peptide distribution does not correspond to the catecholamine distribution. Canine left ventricular tissue sections were processed for immunohistochemistry with the MEAP antibody. Fluorescence was distributed throughout the myocytes and concentrated in ordered lines perpendicular to the myocyte longitudinal axis corresponding to the area of the intercalated disc. This suggests opioids may be important in communication between cardiomyocytes, and possibly the presence of a unique peptide secretory mechanism utilizing the intercalated disc. The relative peptide content in cat and pig hearts was similar to the dog; however, the distribution was different. Feline cardiac ME content was distributed 2:1 in favor of the ventricles and corresponded with a preferential ventricular norepinephrine distribution. The MEAP-IR pattern gave a ventricular/atrial ratio lower (3:5:1) in cat heart vs. dog (5:1). In contrast, pig heart ME and MEAP-IR ventricular/atrial ratios were reversed for both ME (1:10) and MEAP (1:2). HPLC of pig left ventricle showed that MEAP and peptide B represented 33% of the MEAP-IR, respectively. These species variations may correlate to the differences observed in cardiac function. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Peptides Elsevier

Methionine-enkephalin-Arg-Phe immunoreactivity in heart tissue

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Publisher
Elsevier
Copyright
Copyright © 1995 Elsevier Ltd
ISSN
0196-9781
DOI
10.1016/0196-9781(95)02012-L
Publisher site
See Article on Publisher Site

Abstract

Previous findings of enkephalins in cardiac tissue led us to investigate enkephalin distribution in animal models used for cardiovascular research. Canine cardiac methionine-enkephalin (ME) concentrations are low and evenly distributed between atria (4.2 ± 0.6 fmol/mg protein, n = 30) and ventricles (4.4 ± 0.5). In contrast, methionine-enkephalyl-arginyl-phenylalanine (MEAP) immunoreactivity (IR) is higher and preferentially concentrated in the ventricle (112 ± 12) vs. the atria (23.2 ± 2.6 fmol/mg protein). HPLC analysis suggests the atrial/ventricular difference is partly due to altered posttranslational processing. Nearly 90% of ventricular IR is comprised of MEAP (46%) and peptide B (40%) whereas these peptides represent less than half of the atrial content. A nonneuronal localization is indicated because the peptide distribution does not correspond to the catecholamine distribution. Canine left ventricular tissue sections were processed for immunohistochemistry with the MEAP antibody. Fluorescence was distributed throughout the myocytes and concentrated in ordered lines perpendicular to the myocyte longitudinal axis corresponding to the area of the intercalated disc. This suggests opioids may be important in communication between cardiomyocytes, and possibly the presence of a unique peptide secretory mechanism utilizing the intercalated disc. The relative peptide content in cat and pig hearts was similar to the dog; however, the distribution was different. Feline cardiac ME content was distributed 2:1 in favor of the ventricles and corresponded with a preferential ventricular norepinephrine distribution. The MEAP-IR pattern gave a ventricular/atrial ratio lower (3:5:1) in cat heart vs. dog (5:1). In contrast, pig heart ME and MEAP-IR ventricular/atrial ratios were reversed for both ME (1:10) and MEAP (1:2). HPLC of pig left ventricle showed that MEAP and peptide B represented 33% of the MEAP-IR, respectively. These species variations may correlate to the differences observed in cardiac function.

Journal

PeptidesElsevier

Published: Jan 1, 1995

References

  • Local endogenous opiate activity in dog myocardium: Receptor blockade with naloxone
    Caffrey, J.L.; Gaugl, J.F.; Jones, C.E.
  • Intrinsic cardiac enkephalins inhibit vagal bradycardia in the dog
    Caffrey, J.L.; Mateo, Z.; Napier, L.D.; Gaugl, J.F.; Barron, B.A.
  • Naloxone enhances the myocardial responses to isoproterenol in the dog isolated heart-lung
    Caffrey, J.L.; Wooldridge, C.B.; Gaugl, J.F.
  • Cardiovascular effects of endogenous opiate systems
    Holaday, J.W.
  • Translation of heart preproenkephalin mRNA and secretion of enkephalin peptides from cultured cardiac myocytes
    Springhorn, J.P.; Claycomb, W.C.

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