title: Inhibitory actions of polysaccharide sulfate on action potentials and contraction of papillary muscles in guinea pigs.
abstract: OBJECTIVE
  To examine the effects of polysaccharide sulfate (PSS) on the action potentials and contractile force in guinea pig papillary muscles.
  
  
  METHODS
  Using intracellular microelectrode to record fast (FAP) and slow (SAP) action potentials.
  
  
  RESULTS
  PSS (> or = 50 mg.L-1) caused concentration-dependent decreases in the contractile force and the action potential duration (APD) of FAP without affecting the resting potential (RP), action potential amplitude (APA), and maximal upstroke velocity (Vmax). The Vmax, APA, and APD of BaCl2-induced SAP were concentration-dependently decreased by PSS (> or = 15 mg.L-1) and the effects were antagonized by isoprenaline (1 mumol.L-1). The APA and APD of isoprenaline-induced SAP were decreased by PSS (> or = 15 mg.L-1) in a concentration-dependent manner and the effects were attenuated by elevation of extracellular Ca2+ concentration.
  
  
  CONCLUSIONS
  PSS selectively inhibited the slow inward current.
authors.affiliation: Department of Physiology, Henan Medical University, Zhengzhou, China. sbtang@hy.henmu.edu.cn
authors.forename: Y
authors.initials: Y
authors.lastname: Tang
authors.forename: S B
authors.initials: SB
authors.lastname: Tang
authors.forename: H Y
authors.initials: HY
authors.lastname: Zhang
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000502:physiology*; D011134:Polysaccharides / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D011134:Polysaccharides; D002118:Calcium