Electron microscopy and microcalorimetry of the postnatal rat heart (Rattus norvegicus).
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Electron microscopy and microcalorimetry of the postnatal rat heart (Rattus norvegicus). / Mühlfeld, C; Singer, Dominique; Engelhardt, N; Richter, J; Schmiedl, A.
in: COMP BIOCHEM PHYS A, Jahrgang 141, Nr. 3, 3, 2005, S. 310-318.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - Electron microscopy and microcalorimetry of the postnatal rat heart (Rattus norvegicus).
AU - Mühlfeld, C
AU - Singer, Dominique
AU - Engelhardt, N
AU - Richter, J
AU - Schmiedl, A
PY - 2005
Y1 - 2005
N2 - The interplay of ultrastructure and tissue metabolism was examined in neonatal, infant and adult rat hearts by electron microscopy and microcalorimetry. Morphometry was used to determine parameters of oxygen diffusion capacity (distance between capillaries and mitochondria, capillary surface density) and oxidative metabolic capacity (mitochondrial volume fraction). Thin slices and large samples of living tissue were examined calorimetrically to quantify aerobic metabolism and ischemia tolerance, respectively. After birth, rat hearts grow in parallel to body mass and show characteristics of cellular hypertrophy. Capillary surface density increases from neonatal to infant rats, and decreases to an intermediate value in adult rats. The distance between capillaries and mitochondria shows no significant changes throughout postnatal development. Mitochondrial volume fraction increases continuously until adulthood. The specific aerobic tissue metabolic rate is higher in the neonatal than in the infant and adult rat. However, the ischemic decline in metabolic rate is much slower in the neonatal rat, reflecting an elevated hypoxia tolerance. In conclusion, the neonatal rat heart exhibits a high metabolic rate despite a low mitochondrial volume fraction. The subsequent structural rearrangements can be interpreted as long-term adaptations to the increased postnatal workload and may contribute to the progressive loss of hypoxia tolerance.
AB - The interplay of ultrastructure and tissue metabolism was examined in neonatal, infant and adult rat hearts by electron microscopy and microcalorimetry. Morphometry was used to determine parameters of oxygen diffusion capacity (distance between capillaries and mitochondria, capillary surface density) and oxidative metabolic capacity (mitochondrial volume fraction). Thin slices and large samples of living tissue were examined calorimetrically to quantify aerobic metabolism and ischemia tolerance, respectively. After birth, rat hearts grow in parallel to body mass and show characteristics of cellular hypertrophy. Capillary surface density increases from neonatal to infant rats, and decreases to an intermediate value in adult rats. The distance between capillaries and mitochondria shows no significant changes throughout postnatal development. Mitochondrial volume fraction increases continuously until adulthood. The specific aerobic tissue metabolic rate is higher in the neonatal than in the infant and adult rat. However, the ischemic decline in metabolic rate is much slower in the neonatal rat, reflecting an elevated hypoxia tolerance. In conclusion, the neonatal rat heart exhibits a high metabolic rate despite a low mitochondrial volume fraction. The subsequent structural rearrangements can be interpreted as long-term adaptations to the increased postnatal workload and may contribute to the progressive loss of hypoxia tolerance.
M3 - SCORING: Zeitschriftenaufsatz
VL - 141
SP - 310
EP - 318
JO - COMP BIOCHEM PHYS A
JF - COMP BIOCHEM PHYS A
SN - 1095-6433
IS - 3
M1 - 3
ER -
