Cardioprotective effect of EGb 761 on myocardial ultrastructure of young and old rat heart and antioxidant status during acute hypoxia.
OBJECTIVE
Acute hypoxia is a threatening clinical case of emergency and may result in ultrastructural damage, with complete loss of cellular and organ functions. However, little is known about the differences in hypoxia tolerance between young and old myocardia and the protective effects of radical scavenging agents in acute hypoxic stress situations.


METHODS
We investigated the age-dependent differences of the myocardial ultrastructure and antioxidative status (superoxide-dismutase (SOD) activity and malondialdehyde (MDA) content) of young (6 months) and old (22-24 months) Wistar rats (Crl (Wi)Br) after acute respiratory hypoxia of 20 min at 5% v/v O2 in N2O mixture, and the protective effect of Ginkgo biloba extract (EGb 761).


RESULTS
Ultrastructural-morphometric and biochemical age analysis only revealed a decrease in the sarcoplasma volume fraction, an increase in homogeneous intramitochondrial areas, significant higher SOD activity and lower MDA levels in the group of old rats. Pretreatment with EGb 761 led to a significant decrease in MDA content in both control groups. Acute hypoxic stress increased the volume fractions of sarcoplasmatic reticulum, t-tubules, vacuoles, and lipid droplets, and caused mitochondrial swelling, with a more significant increase in degenerated and homogeneous intramitochondrial areas in the old group. SOD activity decreased only in the old hypoxic group; MDA content fell in both. Pretreatment with EGb 761 reduced ultrastructural-morphometric hypoxic damage in both groups, significantly below the levels of control. Young rat myocardium showed significantly higher SOD activity after hypoxia than untreated or older specimens.


CONCLUSIONS
Better hypoxia tolerance is demonstrated by the young myocardium, and an obvious hypoxia-protective effect of EGb 761 in both age groups.
Mozet
Christian
C
Institute of Anatomy, Department of Medicine, University of Leipzig, Leipzig, Germany. christian.mozet@medizin.uni-leipzig.de
Martin
Rosemarie
R
Welt
Klaus
K
Fitzl
Günther
G
D000375:Aging / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002316:Cardiotonic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D022083:Cytoplasmic Structures / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D005260:Female; D020441:Ginkgo biloba; D000860:Hypoxia / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000473:pathology / Q000648:ultrastructure; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D013482:Superoxide Dismutase / Q000378:metabolism; D000096983:Ginkgo Extract
D000975:Antioxidants; D002316:Cardiotonic Agents; D008315:Malondialdehyde; D010936:Plant Extracts; D013482:Superoxide Dismutase; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract