Mesenteric vasodilatory action of testosterone: influence of gender, vessels size and patient age

Hall J1, Jones RD1, Clarke S1, Shorthouse AJ2, Adam IJ2, Brown S2, Jones TH1 and Channer KS2,3. 1Academic Unit of Endocrinology, Division of Genomic Medicine, The University of Sheffield. 2Sheffield Teaching Hospitals NHS Foundation Trust. 3Faculty of Health & Well-being, Sheffield Hallam University.

Testosterone has been shown to cause dilatation in a variety of vascular beds in many animal models. The aim of the current study was to determine whether testosterone has a similar vasodilatory action in the human mesenteric circulation. Differences in dilatation may arise as a consequence of gender, vessel diameter and patient age. We therefore examined the influence of these factors in the dilatory response to testosterone.

The study was approved by the relevant local Ethics Committee, and full written informed consent was given by all patients. Mesenteric tissue was obtained at surgery from male (n = 6, age = 57 ± 4yrs) and female (n = 6, age = 67 ± 4yrs) patients undergoing resections for bowel carcinoma and was macroscopically normal. Mesenteric arteries were carefully dissected and loaded in a wire myograph and maintained at a tension equivalent to the in vivo pressure (100mmHg) in oxygenated krebs at 37 ° C. Endothelial status was confirmed by exposure to acetylcholine (1 µM) following preconstriction with U46619 (1 µM). Vessels were then left to equilibrate in fresh krebs plus ethanol vehicle for 30 min. A cumulative concentration response curve to U46619 (1-1000 nM) was then obtained and testosterone (10nM-100 µM) or equivalent concentrations of ethanol vehicle were then added cumulatively and changes in tension recorded. Analysis of the response to testosterone was then made in vessels obtained from males and females, those <500 µm and ≥ 500 µm in diameter and those from patients < 65yrs and ≥ 65yrs.

Table 1. Demonstrating the vasodilatatory response to testosterone. All p>0.05, analysed via ANOVA.

There were no differences in the dilatory response to testosterone dependent on gender, vessel diameter or age of the patients. Results are expressed as % dilatation from baseline, corrected for the negligible vasopressor ethanol response, (Table 1), as mean ± SEM. This study demonstrates that testosterone induces dilatation in isolated human mesenteric vessels. This response is independent of gender, vessel size and patient age.