Abstract
The distribution of a new local anesthetic, 2-methyl-2-n-propylaminopropion-o-toluide hydrochloride (LA-012) in guinea pigs was studied by the whole body autoradiographic technique.The drug labelled with tritium (3H-LA-012) was injected subcutaneously in the animals, and their whole body sections with about 40 microns in thickness were prepared using cold microtome at various intervals from 10 minutes to 24 hours after the injection. Whole body autoradiographic picture were developed after the sections were exposed to the films for about 5 weeks. The autoradiogram revealed that 3H-LA-012 was absorbed rapidly and a little or no radioactivity was remained at the site of injection after 60 minutes. The radioactivity in the liver, kidney, gastrointestinal contents, gall bladder, salivary gland and infraorbital gland reached to the highest density after about 30 minutes. This rapid accumulation was followed by a slow decline, but the autoradio gram at 24 hours showed only a faint activity in the liver and intestinal tract. A characteristic high accumulation and retention of radioactivity was found in the various connective tissues, such as dense connective tissue in the derma, tendon, auricular cartilage, costal cartilage and so on.
