Comparison of anti-desmin and anti-actin staining for the computerized analysis of cavernous smooth muscle density

To compare the staining properties of anti-desmin and anti-actin in cavernous biopsies and thus determine the optimal antibody for quantifying intracavernous smooth muscle content in the evaluation of erectile dysfunction.

Twenty-two penile biopsies were taken from five normal potent patients, seven with venous leak and 10 with arterial disease, with mean ages of 34.4, 48.8 and 54.8 years, respectively. Biopsies were sectioned and successive sections stained immunohistochemically with antibodies for actin or desmin. Image analysis was used to quantify the proportion of smooth muscle fibres in the cavernous tissue.

There was a significant difference (P = 0.0001) between the mean percentage of cavernous smooth muscle fibres in normal potent men, stained with anti-desmin (38.5%, SD 3.2) or anti-actin (45.2%, SD 3.2) and that in the venous group (anti-desmin 27.4%, SD 4.0%; anti-actin 34.2%, SD 5.3%) or the arteriogenic group (anti-desmin 23.7%, SD 4.4, anti-actin 28.9%, SD 4.9). There was no significant difference in the estimates with either staining method between the venogenic and arteriogenic patients. There was a direct relationship between the cavernous smooth muscle density estimated by anti-desmin and anti-actin staining (r = 0.96).

The anti-actin and anti-desmin staining methods gave equivalent results for discriminating between normal and impotent patients on the basis of the percentage of cavernous muscle fibres. However, anti-actin staining tended to be more sensitive than anti-desmin.