Limits...
3D IMAGING OF THE MITOCHONDRIAL REDOX STATE OF RAT HEARTS UNDER NORMAL AND FASTING CONDITIONS.

Xu HN, Zhou R, Moon L, Feng M, Li LZ - J Innov Opt Health Sci (2014)

Bottom Line: No significant change in Fp was found (p = 0.4).The NADH/Fp ratio decreased with a marginal p value (0.076).The experimental observation of NADH decrease induced by dietary restriction in the heart at tissue level has not been reported to our best knowledge.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA ; Britton Chance Laboratory of Redox Imaging, Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.

ABSTRACT
The heart requires continuous ATP availability that is generated in the mitochondria. Although studies using the cell culture and perfused organ models have been carried out to investigate the biochemistry in the mitochondria in response to a change in substrate supply, mitochondrial bioenergetics of heart under normal feed or fasting conditions has not been studied at the tissue level with a sub-millimeter spatial resolution either in vivo or ex vivo. Oxidation of many food-derived metabolites to generate ATP in the mitochondria is realized through the NADH/NAD(+) couple acting as a central electron carrier. We employed the Chance redox scanner - the low-temperature fluorescence scanner to image the three-dimensional (3D) spatial distribution of the mitochondrial redox states in heart tissues of rats under normal feeding or an overnight starvation for 14.5 h. Multiple consecutive sections of each heart were imaged to map three redox indices, i.e., NADH, oxidized flavoproteins (Fp, including flavin adenine dinucleotide (FAD)) and the redox ratio NADH/Fp. The imaging results revealed the micro-heterogeneity and the spatial distribution of these redox indices. The quantitative analysis showed that in the fasted hearts the standard deviation of both NADH and Fp, i.e., SD_NADH and SD_Fp, significantly decreased with a p value of 0.032 and 0.045, respectively, indicating that the hearts become relatively more homogeneous after fasting. The fasted hearts contained 28.6% less NADH (p = 0.038). No significant change in Fp was found (p = 0.4). The NADH/Fp ratio decreased with a marginal p value (0.076). The decreased NADH in the fasted hearts is consistent with the cardiac cells' reliance of fatty acids consumption for energy metabolism when glucose becomes scarce. The experimental observation of NADH decrease induced by dietary restriction in the heart at tissue level has not been reported to our best knowledge. The Chance redox scanner demonstrated the feasibility of 3D imaging of the mitochondrial redox state in the heart and provides a useful tool to study heart metabolism and function under normal, dietary-change and pathological conditions at tissue level.

No MeSH data available.


Related in: MedlinePlus

Sample embedding orientations (a) and (b) and the photos of the last scanned sections of the rat hearts embedded in the way as shown in (a), where on the left is the control heart corresponding to Fig. 2 and on the right is the fasted heart corresponding to Fig. 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4048726&req=5

Figure 1: Sample embedding orientations (a) and (b) and the photos of the last scanned sections of the rat hearts embedded in the way as shown in (a), where on the left is the control heart corresponding to Fig. 2 and on the right is the fasted heart corresponding to Fig. 3.

Mentions: Organ embedding for redox scanning was conducted the similar way as previously described for tissues.41–43 Briefly, six hearts were embedded with the long axis lying horizontally in parallel with the plane of scanning as shown in Fig. 1(a). Two reference standards (FAD and NADH in Tris-HCl buffer of pH 7 with a concentration of 500 and 100 μM, respectively) were inserted next to the tissue. The seventh heart specimen was excised into two portions. The apical portion (~ 9.4 mm long from the cutting plane to the apex) was used for the present study and was snap-frozen immediately after the excision. Different from the aforementioned embedding orientation, this heart was embedded with the long axis of the heart perpendicular to the scanning plane as shown in Fig 1(b). The entire specimen was exhausted by consecutive scanning spacing of 400 μm.


3D IMAGING OF THE MITOCHONDRIAL REDOX STATE OF RAT HEARTS UNDER NORMAL AND FASTING CONDITIONS.

Xu HN, Zhou R, Moon L, Feng M, Li LZ - J Innov Opt Health Sci (2014)

Sample embedding orientations (a) and (b) and the photos of the last scanned sections of the rat hearts embedded in the way as shown in (a), where on the left is the control heart corresponding to Fig. 2 and on the right is the fasted heart corresponding to Fig. 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048726&req=5

Figure 1: Sample embedding orientations (a) and (b) and the photos of the last scanned sections of the rat hearts embedded in the way as shown in (a), where on the left is the control heart corresponding to Fig. 2 and on the right is the fasted heart corresponding to Fig. 3.
Mentions: Organ embedding for redox scanning was conducted the similar way as previously described for tissues.41–43 Briefly, six hearts were embedded with the long axis lying horizontally in parallel with the plane of scanning as shown in Fig. 1(a). Two reference standards (FAD and NADH in Tris-HCl buffer of pH 7 with a concentration of 500 and 100 μM, respectively) were inserted next to the tissue. The seventh heart specimen was excised into two portions. The apical portion (~ 9.4 mm long from the cutting plane to the apex) was used for the present study and was snap-frozen immediately after the excision. Different from the aforementioned embedding orientation, this heart was embedded with the long axis of the heart perpendicular to the scanning plane as shown in Fig 1(b). The entire specimen was exhausted by consecutive scanning spacing of 400 μm.

Bottom Line: No significant change in Fp was found (p = 0.4).The NADH/Fp ratio decreased with a marginal p value (0.076).The experimental observation of NADH decrease induced by dietary restriction in the heart at tissue level has not been reported to our best knowledge.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA ; Britton Chance Laboratory of Redox Imaging, Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.

ABSTRACT
The heart requires continuous ATP availability that is generated in the mitochondria. Although studies using the cell culture and perfused organ models have been carried out to investigate the biochemistry in the mitochondria in response to a change in substrate supply, mitochondrial bioenergetics of heart under normal feed or fasting conditions has not been studied at the tissue level with a sub-millimeter spatial resolution either in vivo or ex vivo. Oxidation of many food-derived metabolites to generate ATP in the mitochondria is realized through the NADH/NAD(+) couple acting as a central electron carrier. We employed the Chance redox scanner - the low-temperature fluorescence scanner to image the three-dimensional (3D) spatial distribution of the mitochondrial redox states in heart tissues of rats under normal feeding or an overnight starvation for 14.5 h. Multiple consecutive sections of each heart were imaged to map three redox indices, i.e., NADH, oxidized flavoproteins (Fp, including flavin adenine dinucleotide (FAD)) and the redox ratio NADH/Fp. The imaging results revealed the micro-heterogeneity and the spatial distribution of these redox indices. The quantitative analysis showed that in the fasted hearts the standard deviation of both NADH and Fp, i.e., SD_NADH and SD_Fp, significantly decreased with a p value of 0.032 and 0.045, respectively, indicating that the hearts become relatively more homogeneous after fasting. The fasted hearts contained 28.6% less NADH (p = 0.038). No significant change in Fp was found (p = 0.4). The NADH/Fp ratio decreased with a marginal p value (0.076). The decreased NADH in the fasted hearts is consistent with the cardiac cells' reliance of fatty acids consumption for energy metabolism when glucose becomes scarce. The experimental observation of NADH decrease induced by dietary restriction in the heart at tissue level has not been reported to our best knowledge. The Chance redox scanner demonstrated the feasibility of 3D imaging of the mitochondrial redox state in the heart and provides a useful tool to study heart metabolism and function under normal, dietary-change and pathological conditions at tissue level.

No MeSH data available.


Related in: MedlinePlus