Physiological growth of arteries in the rat heart parallels the growth of capillaries, but not of myocytes.
Maladaption to hemodynamic overload, especially to arterial hypertension, has important clinical implications, and it is necessary to obtain criteria in order to discriminate physiological and pathological growth processes. We investigated the physiological growth of intramyocardial arteries in the rat heart. A new stereological method was introduced to determine the length of intramyocardial arteries from counts on histological sections. Four groups of male Sprague-Dawley rats of different ages were investigated. The growth rate of arteries was characterized by the growth coefficient b according to the exponential function y = axb (allometric growth function). Analysis of left ventricular weights (LVW) and total lengths of left ventricular intramyocardial arteries (L) revealed Lv = constant.LVW0.71 (r = 0.77, P < 0.001). The growth coefficient b < 1 indicates that the arterial supply of the heart, i.e. the length density of arteries Lv (length per unit myocardial volume), decreases during normal growth. Empirically, we found L = constant.LVW-0.28 (r = 0.43, P < 0.01). Previously, we estimated growth rates of b = 0.33 for the total length of left ventricular myocytes and b = 0.71 for the total length of capillaries. Thus, growth of intramyocardial arteries considerably exceeds the length increase of myocytes, but is proportional to the length increase of capillaries. Growth analysis of total mitochondrial volume using historical data of our group revealed proportionality to arteries, as well (b = 0.76). This indicates that growth of arteries and capillaries may be determined by oxygen consumption.
Wiest
G
G
Department of Pathology, University of Heidelberg, Germany.
Gharehbaghi
H
H
Amann
K
K
Simon
T
T
Mattfeldt
T
T
Mall
G
G
D000818:Animals; D002196:Capillaries / Q000254:growth & development*; D002455:Cell Division / Q000502:physiology; D003331:Coronary Vessels / Q000254:growth & development*; D008297:Male; D009206:Myocardium / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results