Characterization of the vasculature supplying the genital tissues in female rats

Abstract

Introduction: The internal pudendal arteries are the key resistance vessels controlling the peripheral circulatory component of sexual responses in both male and females. Previous studies in the male rat demonstrated that this vessel has markedly heightened susceptibility to vascular damage compared with other vessels in the body. Evidence suggests that the female may also be susceptible to vascular pathologies contributing to sexual dysfunction.

Aim: The aim of this study is to characterize the anatomical, morphological, and functional properties of the pudendal artery in female rats.

Methods: The pelvic arteries in young Sprague-Dawley female rats were dissected to generate a composite representation of the vascular gross anatomy. Morphometry was performed on perfusion-fixed pudendal arteries whereas others were mounted in a wire myograph to assess responses to vasoactive drugs. These measures were contrasted with a previous study examining male rats.

Main outcome measures: Outcome measures used are gross anatomy, lumen diameter, wall thickness, cross-sectional area, and contractile responses in the internal pudendal artery.

Results: The gross anatomy of the pudendal artery in female rats appears to parallel that found in male rats, acting as the primary feeder vessel of the clitoral, labial, and vaginal tissue. Compared with the male rat, the female pudendal artery has a smaller lumen diameter (169 ± 5.7 vs. 303 ± 13.8 µm), wall thickness (14 ± 0.7 vs. 47 ± 2.2 µm), and cross-sectional area (8 ± 0.4 vs. 52 ± 3.4 × 103 µm(2) ). These structural differences also translate into a decreased contractile capacity of the pudendal arteries from female rats vs. male rats (8.1 ± 2.7 vs. 20 ± 1.4 mN).

Conclusions: Although the gross anatomical features of the vasculature tree supplying the genital tissue in male and female rats appear to have similarities, the tissue-specific properties of the vessel itself have a very different structure-function balance. We hypothesize that this discordance likely reflects the very different sex-specific roles of this vessel in regulating blood flow during arousal.