Enzyme histochemical studies on rat lungs I. An improved technique for the demonstration of enzyme activity in alveolar tissue

Synopsis Rat lungs were supported by ten different materials in an attempt to compare the quality of the sections obtained and to assess the effects of these materials on the activities of three enzyme systems in alveolar tissue as determined by histochemical techniques.Most of the supportive materials were not removed during enzyme incubation and caused some apparent inhibition of enzyme activity. Of the compounds investigated, 0.5% polyethylene glycol was found to produce the most satisfactory results with the least distortion or compression of the alveolar tissue and no apparent inhibition of the three enzymes studied, lactate dehydrogenase, non-specific esterase and alkaline phosphatase. Some of the materials investigated, notably acacia and carboxymethylcellulose, appeared to decrease the thickness of the alveolar wall. This effect was only seen in lungs supported by the most viscous materials.