title: Sildenafil Increases the p50 and Shifts the Oxygen-Hemoglobin Dissociation Curve to the Right.
abstract: BACKGROUND
  Sildenafil (Viagra®) is a selective phosphodiesterase type 5 (PDE5) inhibitor that block the breakdown of cyclic guanyl monophosphate (cGMP) leading to relaxation of the smooth muscles of the corpus cavernous and an increase in blood flow resulting in penile erection. It is hypothesized that sildenafil will increase the release of oxygen from erythrocytes and shift the oxygen-hemoglobin curve to the right.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effect of varying doses of sildenafil on the p50 of the oxygen-hemoglobin dissociation curve in blood samples from eight (8) healthy adult male volunteers with normal hemoglobin HbAA.
  
  
  METHODS
  The hemox-analyzer was used to generate the p50 and the oxygen-hemoglobin dissociation curves.
  
  
  METHODS
  The effect of different doses of sildenafil on the p50 values and shift of the oxygen-hemoglobin curve were the main outcome measures.
  
  
  RESULTS
  Sildenafil caused a statistically significant increase in the p50 values and rightward shift of the oxygen-hemoglobin dissociation curve.
  
  
  CONCLUSIONS
  Sildenafil caused a dose-dependent increase in the release of oxygen from the erythrocytes as shown by the increased p50 values and rightward shift of the oxygen-hemoglobin dissociation curve. Ellis SS and Pepple DJ. Sildenafil increases the p50 and shifts the oxygen-hemoglobin dissociation curve to the right.
authors.affiliation: Department of Basic Medical Sciences, The University of the West Indies, Kingston, Jamaica.
authors.forename: Shantol Sastrice
authors.initials: SS
authors.lastname: Ellis
authors.affiliation: Department of Basic Medical Sciences, The University of the West Indies, Kingston, Jamaica.
authors.forename: Dagogo John
authors.initials: DJ
authors.lastname: Pepple
mesh_terms: D000328:Adult; D006452:Hemoglobinometry / Q000295:instrumentation; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects*; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000187:drug effects*; D010410:Penile Erection / Q000187:drug effects*; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology*; D015203:Reproducibility of Results; D000068677:Sildenafil Citrate / Q000494:pharmacology*
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; D058986:Phosphodiesterase 5 Inhibitors; D000068677:Sildenafil Citrate; D010100:Oxygen
keywords: Oxygen-Hemoglobin Dissociation Curve; Sildenafil; p50