Glucagon and a glucagon-GLP-1 dual-agonist increases cardiac performance with different metabolic effects in insulin-resistant hearts.
OBJECTIVE
The prevalence of heart disease continues to rise, particularly in subjects with insulin resistance (IR), and improved therapies for these patients is an important challenge. In this study we evaluated cardiac function and energy metabolism in IR JCR:LA-cp rat hearts before and after treatment with an inotropic compound (glucagon), a glucagon-like peptide-1 (GLP-1) receptor agonist (ZP131) or a glucagon-GLP-1 dual-agonist (ZP2495).


METHODS
Hearts from IR and lean JCR:LA rats were isolated and perfused in the working heart mode for measurement of cardiac function and metabolism before and after addition of vehicle, glucagon, ZP131 or ZP2495. Subsequently, cardiac levels of nucleotides and short-chain CoA esters were measured by HPLC.


RESULTS
Hearts from IR rats showed decreased rates of glycolysis and glucose oxidation, plus increased palmitate oxidation rates, although cardiac function and energy state (measured by ATP/AMP ratios) was normal compared with control rats. Glucagon increased glucose oxidation and glycolytic rates in control and IR hearts, but the increase was not enough to avoid AMP and ADP accumulation in IR hearts. ZP131 had no significant metabolic or functional effects in either IR or control hearts. In contrast, ZP2495 increased glucose oxidation and glycolytic rates in IR hearts to a similar extent to that of glucagon but with no concomitant accumulation of AMP or ADP.


CONCLUSIONS
Whereas glucagon compromised the energetic state of IR hearts, glucagon-GLP-1 dual-agonist ZP2495 appeared to preserve it. Therefore, a glucagon-GLP-1 dual-agonist may be beneficial compared with glucagon alone in the treatment of severe heart failure or cardiogenic shock in subjects with IR.
Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, and Metabolic and Cardiovascular Diseases Laboratory, Edmonton, AB, Canada. lax@sund.ku.dk
L N
LN
Axelsen
W
W
Keung
H D
HD
Pedersen
E
E
Meier
D
D
Riber
A L
AL
Kjølbye
J S
JS
Petersen
S D
SD
Proctor
N-H
NH
Holstein-Rathlou
G D
GD
Lopaschuk
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology*; D052216:Glucagon-Like Peptide 1 / Q000819:agonists*; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D057809:HEK293 Cells; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D010084:Oxidation-Reduction; D010168:Palmitates / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology*; D051381:Rats
D002316:Cardiotonic Agents; D010168:Palmitates; D010455:Peptides; D052216:Glucagon-Like Peptide 1; D000255:Adenosine Triphosphate; D005934:Glucagon; D005947:Glucose