title: Possible mechanism of inotropic and chronotropic effects of Rosa damascena on isolated guinea pig heart.
abstract: BACKGROUND
  The possible mechanism(s) of inotropic and chronotropic effects of the extract from Rosa damascena (R. damascena) on heart was examined.
  
  
  METHODS
  Inotropic and chronotropic effects of four concentrations of the extract from R. damascena and isoprenaline were examined in isolated guinea-pig hearts perfused through aorta in a Langendorff model. All measurements were performed in three different groups: 1) In the presence and absence of propranolol, 2) In the presence and absence of methacholine and 3) In the presence of diltiazem (n = 12 for each group).
  
  
  RESULTS
  In all groups both isoprenaline and the extract caused an increase in heart rate and contractility (p < 0.05 to p < 0.001). Only in group 1, the final concentration of isoprenaline in the absence of propranolol caused significant greater increase in heart rate compared to the extract (207.6 ± 11.0 compared to 162.6 ± 11.8, p < 0.01). The percent increase in heart contractility due to the final concentration of the extract in the absence (362.4 ± 36.9 compared to 227.7 ± 31.6, p < 0.01) and presence of propranolol (577.1 ± 62.9 compared to 357.5 ± 45.6, p < 0.001) in group 1 and absence (403.7 ± 42.1 compared to 244.8 ± 18.9, p < 0.005) and presence of methcholine (499.88 ± 64.64 compared to 323.90 ± 44.49, p < 0.05) in groups 2 was significantly greater than the increase caused by isoprenaline.
  
  
  CONCLUSIONS
  The results of this study suggest that inotropic and chornotropic effect of R. damascena is possibly due to the stimulatory effect of this plant on beta-adrenoceptors.
authors.affiliation: Applied Physiology Research Centre, School of Medicine, Mashhad University of Medical Sciences, Mashhad, 9177948564, Iran. boskabadymh@mums.ac.ir.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Boskabady
authors.forename: Alaleh
authors.initials: A
authors.lastname: Vatanprast
authors.forename: Haydar
authors.initials: H
authors.lastname: Parsaee
authors.forename: Morteza
authors.initials: M
authors.lastname: Boskabady