CAVERNOSAL EXPANDABILITY IS AN ERECTILE TISSUE MECHANICAL PROPERTY WHICH PREDICTS TRABECULAR HISTOLOGY IN AN ANIMAL-MODEL OF VASCULOGENIC ERECTILE DYSFUNCTION

Purpose: Reliable, clinically available, non-invasive measurements abl e to predict trabecular histology without the need for erectile tissue biopsy would improve impotence management, since the percentage of tr abecular smooth muscle content has been shown to be associated with co rporal veno-occlusive dysfunction. The purpose was to identify whether the erectile tissue mechanical property, cavernosal expandability, co rrelated with the percentage of trabecular smooth muscle content in an animal model of hypercholesterolemia and ischemic-induced corporal fi brosis. Materials and Methods: New Zealand White rabbits (6 to 7 month s old, 3 to 3.5 kg.), were divided into control (n = 7), hypercholeste rolemic (n = 5, 0.5% cholesterol diet) and atherosclerotic groups (n = 8, 0.5% cholesterol diet with balloon de-endothelialization). At 16 w eeks, the corpora cavernosa were removed en bloc and submerged in phys iologic salt solution, and volume-pressure data were plotted at 20 mm. Hg pressure intervals under trabecular smooth muscle relaxation. Cave rnosal expandability, X, (the measure of the ability to achieve high c orporal expansion at relatively low intracavernosal pressure) and tuni cal distensibility, V-E/V-F, (relative volume of fully erect to flacci d penis) were calculated. Erectile tissue was assessed by computer-ass isted color histomorphometry with Masson's trichrome stained sections (30 to 45 high power fields/animal) to assess percentage of trabecular smooth muscle content. Results: The overall mean percentage of trabec ular smooth muscle content and mean cavernosal expandability values we re 45.4 +/- 1.6, 39.2 +/- 0.9, 33.9 +/- 0.6 and 0.0165 +/- 3.04 x 10(- 3) 0.0116 +/- 1.63 x 10(-3), 0.0118 +/- 1.26 x 10(-3) mm. Hg-1 for the control, hypercholesterolemic and atherosclerotic groups, respectivel y (r = 0.87). Significant differences in trabecular smooth muscle cont ent were observed among all 3 groups, and in cavernosal expandability, between control and atherosclerotic groups, as well as between contro l and hypercholesterolemic groups but not between atherosclerotic and hypercholesterolemic groups. Conclusions: The erectile tissue mechanic al property, cavernosal expandability, correlated with erectile tissue structural quality. Since cavernosal histology has been shown to pred ict corporal veno-occlusive function, it is hypothesized that the meas urement of cavernosal expandability may become a valuable functional c linical parameter in the diagnosis and treatment of men with erectile dysfunction.