CARNITINE AND CARDIAC INTERSTITIUM

An important part of (acyl)carnitine may be stored in interstitial spa ces and the external surface of adjacent cells. A high concentration o f carnitine in the direct vicinity of cells may enhance the synthesis and export of long-chain acylcarnitine. Long-chain acylcoenzyme A, fro m which long-chain acyl carnitine is formed, cannot penetrate intact c ell membranes. During hypoperfusion or ischemia, when long-chain acylc oenzyme A accumulates due to hampered fatty acid oxidation, there is a n increased formation of long-chain acyl carnitine which diffuses into the interstitium and adjacent vascular endothelial cells. Due to its lipophilic nature and net positive charge (limitation of carboxyl-grou p dissociation in ischemic acidosis), long-chain acyl carnitine may de crease the affinity of Ca2+ to the cell surface and prevent Ca2+ overl oad of cells. The advantage of carnitine over many other cationic amph iphiles in the protection of areas of ischemia is that long-chain acyl carnitine is formed and stored only in ischemic areas.