Transmural hematocrit gradient in left ventricular myocardia of rats.
The transmural distribution of tissue hematocrit was determined in rat left ventricular myocardium. Intramyocardial distribution volumes of 99Tc-labeled red blood cells and 131I-labeled albumin were measured in hearts arrested in a relaxed state by KCl or in a contracted state by BaCl2. Hearts were frozen in situ immediately after arrest by bathing in a mixture of liquid nitrogen and isopentane. After excision of the heart, a parallelepipedic portion was cut in a transverse section of the left ventricular free wall and subjected to en face serial sectioning through the thickness of the wall from the epicardium to the endocardium. 99Tc and 131I activity allowed determination of red blood cell and plasma volume and consequently of tissue hematocrit in each section. In both the relaxed and the contracted states of the hearts, a significant decreasing gradient of tissue hematocrit was found from the outer to the inner layers of myocardium. Tissue hematocrit in the subendocardial layers was approximately 70% of its value in the subepicardial layers.
Vicaut
E
E
Institut National de la Santé et de la Recherche Médicale, U141, Hospital Lariboisière, Paris, France.
Levy
B I
BI
D000818:Animals; D004699:Endocardium / Q000166:cytology; D006352:Heart Ventricles; D006400:Hematocrit; D009206:Myocardium / Q000166:cytology*; D010496:Pericardium / Q000166:cytology; D051381:Rats; D011919:Rats, Inbred Strains