Abstract
Recent evidence suggests that glucagon-like peptide-1 (GLP-1) enhances recovery of left ventricular (LV) function after transient coronary artery occlusion. However, it is uncertain whether GLP-1 has direct effects on normal or ischemic myocardium and whether the mechanism involves increased myocardial glucose uptake. LV function and myocardial glucose uptake and lactate production were measured under basal conditions and after 30 min of low-flow ischemia and 30 min of reperfusion in the presence and absence of GLP-1-(7–36) amide. The response was compared with standard buffer alone or buffer containing insulin (100 μU/ml). GLP-1 decreased the left ventricular developed pressure (baseline: 100 ± 2 mm Hg; GLP-1: 75 ± 3 mm Hg, p < 0.05) and LV dP/dt (baseline: 4876 ± 65 mm Hg/s; GLP-1: 4353 ± 76 mm Hg/s, p < 0.05) in normal hearts. GLP-1 increased myocardial glucose uptake (baseline: 33 ± 3 μmol/min/g; GLP-1: 81 ± 7 μmol/min/g, p < 0.05) by increasing nitric oxide production and glucose transporter (GLUT)-1 translocation. GLP-1 enhanced recovery after 30 min of low-flow ischemia with significant improvements in LV end-diastolic pressure (control: 13 ± 4 mm Hg; GLP-1: 3 ± 2 mm Hg, p < 0.05) and LV developed pressure (control: 66 ± 6 mm Hg; GLP-1: 98 ± 5 mm Hg, p < 0.05). GLP-1 increased LV function, myocardial glucose uptake, and GLUT-1 and GLUT-4 translocation during reperfusion to an extent similar to that with insulin. GLP-1 has direct effects on the normal heart, reducing contractility, but increasing myocardial glucose uptake through a non-Akt-1-dependent mechanism, distinct from the actions of insulin. However, GLP-1 increased myocardial glucose uptake and enhanced recovery of cardiac function after low-flow ischemia in a fashion similar to that of insulin.
Footnotes
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This work was supported in part by United States Public Health Service Grants DA-10480 and AG-023125.
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doi:10.1124/jpet.106.100982.
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ABBREVIATIONS: GLP-1, glucagon-like peptide-1; LV, left ventricular; KH, Krebs-Henseleit; LVEDP, left ventricular end-diastolic pressure; LVDevP, left ventricular developed pressure; GLUT, glucose transporter; MAP, mitogen-activated protein; MAPKAP, MAP kinase-activated protein kinase; NOx, nitrite/nitrate; NO, nitric oxide; DU, density units.
- Received January 4, 2006.
- Accepted February 8, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
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