Structure of cristae in cardiac mitochondria of aged rat

Abstract

Interfibrillar mitochondria (IFM) of the heart in aged Fischer 344 rats show a biochemical defect which might be reflected in their morphology. We examined by high resolution scanning electron microscopy over 5,500 mitochondria to determine if a concomitant structural alteration existed. This methodology provides a means of examining mitochondrial cristae in three dimensions. Cristae of in situ subsarcolemmal mitochondria (SSM) and of IFM in both 6 and 24 month old Fischer rats are predominantly lamelliform. When isolated, these organelles, whether of SSM or IFM origin, display enhanced heterogeneity, but they have similar crista morphology irrespective of the age of the rat. Crista configuration does not play a major role in age-related cardiac mitochondrial defects.Cardiac mitochondria exist in two functionally distinct populations. Subsarcolemmal mitochondria (SSM) are situated beneath the sarcolemma, whereas interfibrillar mitochondria (IFM) reside between the myofibrils (Palmer et al., 1977). Biochemically speaking, aging selectively alters IFM, with the protein yield and rate of oxidative phosphorylation being decreased, but SSM remain unaffected (Fannin et al., 1999). Despite these biochemical differences, transmission electron microscopy does not reveal any obvious morphologic changes in cardiac mitochondria associated with aging (Fannin et al., 1999).Osmium extraction of tissues and pellets of isolated mitochondria combined with high resolution scanning electron microscopy (HRSEM) permits the examination of the interior of these organelles. Our use of osmium extraction-HRSEM allowed us to establish the threedimensional structure of cristae in more than a thousand in situ and isolated cardiac mitochondria in or derived from young adult Sprague-Dawley rats (Riva et al., 2005). SSM contain largely lamelliform cristae; in contrast, cristae in IFM display mostly tubular morphology (Riva et al., 2005). This result provides a morphological underpinning for the Corresponding Author: Charles L. Hoppel, M.D., Case Western Reserve University School of Medicine, Department of Pharmacology, 10900 Euclid Avenue, Cleveland, Phone: (216) FAX: (216) 368-3395, E-mail: charles.hoppel@case.edu Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. previous biochemical studies of rat heart mitochondria that had shown functional differences between SSM and IFM. NIH Public AccessWe now turn our attention to the Fisher 344 rat, a long-established model for aging studies (Coleman et al., 1977). In this aging model, there is a disconnect between metabolic changes, which are highly si...

Physiological and structural differences in spatially distinct subpopulations of cardiac mitochondria: influence of cardiac pathologies

“…These findings complement those of Judge et al (56) who observed increased oxidative stress and antioxidant enzyme activities in the IFM of the aged rat heart. In addition, aging has been associated with a decrease in ETC complex III activity in the IFM of aged rat heart, which has been linked in part to a defect in the cytochrome c binding site of complex III (72), without effect on the IMM lipid environment or cristae morphology (53,68,87,107). Electron leakage at complex III, leading to increased superoxide production (86) and reduction in cytochrome oxidase subunit VIIa, was detected only in the IFM of aged rat hearts (35).…”

Rol de la función mitocondrial en el corazón y sus implicaciones en disfunciones cardíacas

“…Por ende, la pérdida de la función mitocondrial, así como, de cardiomiocitos genera una reducción en la producción de la energía necesaria para el funcionamiento del corazón [30]. El Observatorio Nacional de Salud Colombiano [34] ha determinado que las enfermedades cardiovasculares fueron una de las principales causantes de muerte en Colombia en el periodo entre 1998 y 2011.…”

“…Como ya se ha mencionado, el envejecimiento causa pérdida de la función mitocondrial, lo que conlleva a un aumento en la muerte de los cardiomiocitos a través de la liberación de factores apoptogénicos; proceso mediado por dichas mitocondrias disfuncionales. En el envejecimiento se presentan alteraciones bioquímicas en IFM; caracterizadas por una disminución en el rendimiento proteico, así como, en la velocidad de fosforilación oxidativa, mientras que las SSM, no presentan dichas alteraciones [30]. Sin embargo, en el estudio realizado por Hofer et al [40] en mitocondrias SSM e IFM aisladas de corazón de rata, determinaron que con la edad no hubo aumento en la generación de H 2 O 2 , ni disminución en la velocidad de consumo de oxígeno en IFM y SSM.…”

The Fathers of Italian Histology

“…Bloom and Fawcett, 1994), that mitochondria of such type of cells have tubular and vesicular cristae. Recently, (Riva et al, 2005;Riva et al, 2006) we have successfully applied our technique to investigate structural differences in two biochemically defined populations of isolated rat cardiac mitochondria, and to study the structure of cristae in relation to aging.As can be seen from Figure 8 we have been able to remove all cytoplasmic organelles of serous cells of salivary glands in order to expose the cytoplasmic side of the intercellular canaliculi. In the same preparations we demonstrated regular clusters of particles that we related to cellular junctions .…”

“…Bloom and Fawcett, 1994), that mitochondria of such type of cells have tubular and vesicular cristae. Recently, (Riva et al, 2005;Riva et al, 2006) we have successfully applied our technique to investigate structural differences in two biochemically defined populations of isolated rat cardiac mitochondria, and to study the structure of cristae in relation to aging.…”