title: Intercalated clear cells or pale cells in the sinus node of canine hearts? An ultrastructural study.
abstract: Two types of sinus nodal cells were responsible for the main differences in the literature concerning the ultrastructure of the sinuatrial node: the intercalated clear cells and pale cells. Canine hearts were arrested by (1) aortic cross clamping, (2) coronary perfusion with the cardioplegic solution St. Thomas, and (3) coronary perfusion with the cardioplegic solution HTK (Custodiol(R)). After fixation by immersion or perfusion the sinus node tissue was prepared for electron microscopy. Following cardioplegic arrest and perfusion fixation, three nodal cell types in the non-ischemic sinuatrial node were observed: typical nodal cells, transitional cells, and intercalated clear cells. Less than 1% of the non-ischemic sinuatrial cells were intercalated clear cells, surrounded by typical nodal cells or transitional cells. The contractile apparatus of the intercalated clear cells was extremely poorly developed. Great structural variations in the mitochondria were observed in intercalated clear cells, variations that would not appear under conditions of ischemia. In contrast, after 15-25 min of ischemia at 25 degrees C the appearance of the sinus nodal cells was strikingly different from that of the non-ischemic sinuatrial cells. More than 10% of the nodal cells showed typical ischemic alterations, e.g., mitochondrial swelling, clumping of nuclear chromatin, loss of glycogen particles, and cell swelling in varying degrees. Because they look very pale, these nodal cells have been described as pale cells in the literature. Intercalated clear cells appear mainly in non-ischemic nodal tissue. Pale cells are ischemically damaged sinus nodal cells.
authors.affiliation: Department of Anatomy, Division of Electron Microscopy, University of Göttingen, D-37075 Göttingen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Stoletzki
authors.forename: A
authors.initials: A
authors.lastname: Schmiedl
authors.forename: J
authors.initials: J
authors.lastname: Richter
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D002122:Calcium Chloride / Q000494:pharmacology; D002314:Cardioplegic Solutions / Q000494:pharmacology; D004285:Dogs / Q000033:anatomy & histology*; D005260:Female; D005947:Glucose; D006321:Heart / Q000187:drug effects; D006323:Heart Arrest / Q000473:pathology; D007101:Immersion; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008353:Mannitol; D017202:Myocardial Ischemia / Q000473:pathology; D010477:Perfusion; D011189:Potassium Chloride / Q000494:pharmacology; D011343:Procaine; D012849:Sinoatrial Node / Q000166:cytology* / Q000473:pathology / Q000648:ultrastructure; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D014693:Ventricular Fibrillation / Q000473:pathology
chemical_list: D001639:Bicarbonates; C039984:Bretschneider cardioplegic solution; D002314:Cardioplegic Solutions; C041711:St. Thomas' Hospital cardioplegic solution; D008353:Mannitol; D012965:Sodium Chloride; D011343:Procaine; D011189:Potassium Chloride; D008274:Magnesium; D005947:Glucose; D002122:Calcium Chloride