title: Melatonin effects on megakaryocyte membrane patch-clamp outward K+ current.
abstract: BACKGROUND
  This study was carried out to evaluate the influence of melatonin concentration on rat bone marrow megakaryocyte outward K+ current and its implications with regard to platelet production. It is the Authors' view that the greatly extended development of megakaryocyte membrane, together with its ion channels, makes the choice of this topic particularly pertinent.
  
  
  METHODS
  Megakaryocytes from fresh Wistar rat bone marrow were clampaged with patch-clamp technique and the examination of membrane outward current was performed when melatonin dissolved in external or internal standard solution was used.
  
  
  RESULTS
  On the basis of this study, melatonin does reduce outward K+ current intensity, the more the higher the melatonin concentration. In quantitative terms, whereas no change is noticed when dissolved melatonin concentration in external standard solution is smaller than 25 mM, at 50 mM only a delayed outward current decrease appears. The effect on the outward current intensity is reversible at least until melatonin concentration reaches 500 mM; when melatonin concentration is higher than 1000 mM the effect is demonstrably irreversible. The presence on the megakaryocyte membrane of internal standard melatonin solution does reduce the outward current even more sharply.
  
  
  CONCLUSIONS
  There seems to be a positive correlation between cationic pump and megakaryocyte intimate processes of platelet production.
authors.affiliation: Private Laboratory of Physiology, Modena, Italy. luigidibella@libero.it
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Bella
authors.forename: Carla
authors.initials: C
authors.lastname: Bruschi
authors.forename: Luciano
authors.initials: L
authors.lastname: Gualano
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D008533:Megakaryocytes / Q000187:drug effects* / Q000378:metabolism*; D008550:Melatonin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D008550:Melatonin; D011188:Potassium