Localized embedding of labelled microspheres by microwave heating in tissues of hypothermie dogs

Abstract

In this study a hind leg of dogs was profoundly cooled while the gracilis muscle of the same leg was kept normothermic or slightly hyperthermic (37 to 39 øC) by microwave heating (differential hypothermia). The circulation (measured by trapping of Technetium Tc 99 labelled carbonized microspheres in capillaries) through the warmed muscle tissues was five to 12 times greater than that through the cold muscles of the same leg. When differential hypothermia was used to induce selective embedding of (y9o) Yttrium-loaded microspheres in the warm gracilus muscle of the cooled leg, pronounced damage (or even complete destruction) of normothermic muscle tissue was observed while leaving undamaged all other muscle tissue that was protected by cooling. It is suggested that differential hypothermia might be a useful tool for preferential embedding of biologically important pharmaceuticals or for preferential embedding of medical radio-nuclides whenever a superselective catheterization of tumors or of other tissues is not possible.