Cyclosporin A-induced coronary artery vasoconstriction through myogenic and endothelium-dependent mechanisms.
BACKGROUND
The exact mechanism of vascular toxicity of cyclosporin A (CSA) remains unknown. It has been reported that an impairment of endothelium-mediated vascular reactivity may be involved.


RESULTS
We studied the response to intracoronary injections of acetylcholine (ACh) (30 ng/kg), adenosine (100 ng/kg), and nitroglycerin (NTG) (1.7 micrograms/kg) before and after intracoronary infusion of CSA (20 mg over 20 minutes) and of L-arginine (10 mg.kg-1.min-1). Experiments were performed on 11 open-chest dogs anesthetized and instrumented for measurements of coronary blood flow (CBF) in the left anterior descending (LAD) and left circumflex (LCx) coronary arteries, left ventricular dP/dt, mean aortic pressure, and coronary sinus pressure. CSA, L-arginine, ACh, adenosine, and NTG were injected into the LAD, and the LCx served as control. The increase in CBF in the LAD with ACh administration averaged 21 +/- 11 mL/min before CSA, 15 +/- 10 mL/min after CSA, and 15 +/- 8 mL/min during L-arginine injection (P = .2). Adenosine caused an increase in CBF in the LAD averaging 20 +/- 10 mL/min before CSA, 10 +/- 8 mL/min after CSA, and 17 +/- 12 mL/min during L-arginine injection (P = .004). NTG caused an increase in CBF in the LAD averaging 21 +/- 10 mL/min before CSA, 13 +/- 11 mL/min after CSA, and 14 +/- 7 after administration of L-arginine (P = .009).


CONCLUSIONS
These results suggest that direct intracoronary injection of CSA induces a vasoconstrictive response through endothelium-dependent and myogenic mechanisms. The muscarinic endothelial response was not affected by CSA, whereas the purinergic action of CSA was restored after L-arginine administration.
Department of Surgery, Montreal Heart Institute, Quebec, Canada.
A
A
Khalil
M
M
Carrier
J G
JG
Latour
L C
LC
Pelletier
D000109:Acetylcholine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D016572:Cyclosporine / Q000494:pharmacology*; D004285:Dogs; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D005996:Nitroglycerin / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
D007166:Immunosuppressive Agents; D016572:Cyclosporine; D001120:Arginine; D005996:Nitroglycerin; D000241:Adenosine; D000109:Acetylcholine