title: Cold storage induces an endothelium-independent relaxation to hypoxia/reoxygenation in porcine coronary arteries.
abstract: Tissues are often cold stored for physiological studies and for clinical transplantation. We report that cold storage induces a relaxation to reoxygenation after hypoxia (H/R) in de-endothelialized porcine coronary arteries. In fresh denuded arteries stimulated with U46619, H/R did not elicit relaxation. However, after overnight cold storage (4 degrees C), H/R elicited a transient relaxation with peak relaxation of 56 +/- 8% (n = 8), which was reproducible after 2 days of cold storage. The H/R relaxation was inhibited by methylene blue (10 microM) and LY83583 (10 microM), O2-hemoglobin (1 microM), or N(G)-methyl-L-arginine (0.2 mM), but neither N(G)-nitro-L-arginine (0.2 mM) nor cyclo-oxygenase inhibition was effective. Importantly, the H/R relaxation was attenuated by KCl (40 mM) or tetrabutylammonium chloride (5 mM), a non-selective inhibitor of K+ channels. Interestingly, authentic nitric oxide (NO)- or S-nitroso-N-acetylpenicillamine (SNAP)-induced relaxations were enhanced by cold storage in U46619 (0.1 microM) contractures. When tissues were contracted with KCl (40 mM), the enhancement in NO- or SNAP-induced relaxation by cold storage was markedly smaller than with U46619. Neither catalase (1,200 U/ml) nor 3-amino-triazole (50 mM), an inhibitor of catalase, affected the H/R relaxation. The duration of H/R relaxation also increased with the period of incubation at 37 degrees C in the organ bath. This was blocked by inhibition of NO synthesis or guanylate cyclase. Moreover, inhibition of protein synthesis with actinomycin D (0.1 microM) and cycloheximide (10 microM), or dexamethasone (1 microM), an inhibitor of NO synthase induction, blocked this increase in the duration of the H/R relaxation. The results suggest that in smooth muscle induction of NO pathway relaxation, which is in part mediated by K+ channels and inducible NO synthase, may be of importance to the understanding of ischemia/reperfusion responses in cold-stored arteries.
authors.affiliation: Department of Molecular and Cellular Physiology, University of Cincinnati, College of Medicine, Ohio 45267-0576, USA.
authors.forename: S
authors.initials: S
authors.lastname: Shimizu
authors.forename: K
authors.initials: K
authors.lastname: Shimizu
authors.forename: R J
authors.initials: RJ
authors.lastname: Paul
mesh_terms: D000818:Animals; D003080:Cold Temperature; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D000860:Hypoxia / Q000503:physiopathology*; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D009926:Organ Preservation; D010100:Oxygen / Q000378:metabolism*; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D026423:S-Nitroso-N-Acetylpenicillamine; D013552:Swine; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D010396:Penicillamine; D010100:Oxygen