Semiquantitative estimations of quinacrine fluorescence in intestinal nerve fibres

Quinacrine has been shown to bind selectively to a population of nerves and ganglion cells in the mouse, rat and guinea-pig gut. In the present report a method for semiquantitation of nervous quinacrine contents using semiquantitative estimations of fluorescence intensity and nerve fibre density is presented and evaluated. Estimation of fluorescence intensity and nerve fibre density is based on a scale with eleven steps from 0 to 5. Preparations were incubated in 14C-labelled quinacrine hydrochloride. Reliability of the scale was expressed as the correlation coefficient between two consecutive blind estimations of the same preparations with recoding and remixing specimens in between. This correlation was found to be 0.95 or higher. Validity was expressed as the correlation between the semiquantitative estimations and 14C-quinacrine uptake measurements into the same specimens. Also this correlation was found to be strongly positive. It was concluded that nervous quinacrine content and amount of quinacrine binding nerves can be reliably estimated by fluorescence microscopy.