title: I. Slow oscillations in vaginal blood flow: alterations during sexual arousal in rodents and humans.
abstract: OBJECTIVE
  This study investigated slow oscillatory rhythms in vaginal blood flow as a physiological marker of female sexual arousal in rodents, human healthy volunteers, and women with female sexual arousal disorder (FSAD).
  
  
  METHODS
  Vaginal blood flow was measured in urethane-anesthetized rodents using laser Doppler flowmetry, while in humans, vaginal photoplethysmography was used. Acquired data were filtered for frequency analysis in the range of 0.013-2.5 Hz in rodents and 0.01-0.5 Hz in humans. Rodents were assessed for changes in a high frequency range (HF = 0.6-2.5 Hz), and a low frequency range (LF = 0.013-0.6 Hz). Human data were assessed for total spectral power in the entire frequency range.
  
  
  RESULTS
  During naturally induced arousal (exposure to male), oscillatory rhythms in vaginal blood flow from rodents demonstrated an increase in the ratio of LF oscillations to HF oscillations (LF/HF ratio). Drugs known to induce sexual arousal (apomorphine and melanotan II) were tested in anesthetized rodents. Both compounds induced an increase in the LF/HF ratio. In humans, visual sexual stimulation induced an increase in the total power of slow oscillatory activity in vaginal blood flow in healthy human volunteers. No such increase was observed in women with FSAD.
  
  
  CONCLUSIONS
  This study demonstrated that slow oscillations in vaginal blood flow are correlated with subjective physiological arousal and display diminished responsiveness in women with FSAD. Slow oscillations in vaginal blood flow are entirely independent of vaginal vasocongestion as women with FSAD demonstrated a normal vasocongestion response to visual sexual stimulation. In conditions where rodents would be expected to be sexually aroused, slow oscillations in vaginal blood flow showed a shift from HFs to LFs. This technique will greatly enhance the investigation of female sexual function both clinically and preclinically.
authors.affiliation: Pfizer Global Research and Development-Genitourinary Therapeutic Area, Sandwich, UK.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Allers
authors.forename: Natalie
authors.initials: N
authors.lastname: Richards
authors.forename: Stefan
authors.initials: S
authors.lastname: Sultana
authors.forename: Maria
authors.initials: M
authors.lastname: Sudworth
authors.forename: Toni
authors.initials: T
authors.lastname: Dawkins
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Hawcock
authors.forename: Tim
authors.initials: T
authors.lastname: Buchanon
authors.forename: James H
authors.initials: JH
authors.lastname: Casey
authors.forename: Chris
authors.initials: C
authors.lastname: Wayman
mesh_terms: D000818:Animals; D002755:Choice Behavior; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000294:innervation*; D010775:Photic Stimulation; D017156:Photoplethysmography; D051381:Rats; D020318:Rats, Long-Evans; D012725:Sexual Behavior / Q000523:psychology; D020018:Sexual Dysfunctions, Psychological / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014621:Vagina / Q000098:blood supply*