Identification of genes commonly expressed in both cardiac and oxidative skeletal muscles

NITROSATION CAUSES MITOCHONDRIAL DYSFUNCTION AND CY-TOCHROME C RELEASE IN MYOCARDIUM Aiste Jekabsone & Vilmante Borutaite. Lab of Biochemktry, lnst for Biomed Res, Kaunas Univ of Medicine, Lithuania. NO in tissue is shown to increase during ischemia, so we investigate how NO and NO donors affect heart mitochondria in the absence and presence of increased Ca2’ , another ischemic factor. Mitochondria were isolated by differential mitochondrial respiration was centrifugation; measured by oxygen consumption, membrane redistribution of potential detected from tetraphenylphosphonium ions, NO concentration by NO-meter, complex I activity and cytochrome c+cT content - spectrophotometrically. NO+Ca2’ 02-irreversibly inhibited mitochondrial function by inactivating complex I and induced cytochrome c release; this was prevented by ONOO’ scavengers and reversed by light and thiols. NO donor NOC-18 with Ca2* also inhibited complex I in the ONOO-- scavengers-sensitive and light&thiol-reversible manner, but nitrosogluthation caused the same effects without Ca2’ In conclusion, NO+Ca” affect mitochondria via increase of ONOO- which nitrosates critical SH groups in complex I and release cytochrome c. VERAPAhWL INHWTS ATP-SENSITIVE POTASSIUM CHANNEL ACTIVATION IN THE CORONARlES Alexandrr Juhau-Nagy (L.Vloletta K6kesl. Dept. of Cardlovasculrr Surgery, Semmelweis University, Budapest, Hungary The coronary vasodllator action of ATP-sensitive potassium (KATp) channel activators would be expected to be augmented when the open state probability of L-type Ca channels decreases. Supposing a more sophisticated Interaction, experiments were undertaken to determine how the pharmacologic activation in the coronary bed of Knrp channels IS infiuenced by Ca channel blockade. In open chest dogs coronary blood flow (CBF) was measured with an ultrasonic probe. Blood pressure, heart rate, and left ventricular contractile force were also recorded. Successve dose response curves were constructed by admimstering bolus doses of the KAIp activator pinacidil (5. 10. 20, 40 vglkg I.v.) which elicited lasting coronary vasodilator responses. Increasing cumulative doses of verapamil (0.1, 0.2, 0.4, 0.8 mglkg i.v.) dose-dependently shlfted these curves to the right. Maximal changes of CBF due to KliTP activation

were

reduced,

under

the

influence

of increaslng

verapamil effects, from the control of 64.61t13.0 to 61.318 I, 53.4H.l. 40&4.5’, and 27.5G.6” AmUmin, while the maxima of changes in coronary vascular conductance (Row/pressure) decreased from l&Q+1 4 to 144+15. 124+9”. 109i8*’ and 73+8” A%, respectively (n=7. mean+SEM. pco.05, * p
l

FATTY ACID PROFILE IN THE HEART OF CHRONICALLY HYPOXIC RATS: EFFECT OF ACUTE ISCHEMIA ‘Jana JeikovB, ‘Olga NovikovP, ‘Frantigek Kohif, ‘Eva TvrzickB, ‘Jan NeckBT, ‘FraatiSek NovPk. ‘Dept. of Biochemistry and *Animal Physiology, Faculty of Science, ‘1st Facultv of Medicine. Charles Universitv. ‘Institute of Physiology* Acad. Sci. CR and Centre forS&erimental Cardiovascular Research, Prague, Czech Republic

LIPID

Adaptation of rats to intermittent high altitude (IHA) hypoxia Increases resistance of their hearts to acute ischemic injury. We examined whether chronic hypoxia affects the profile of fatty acids (FA) in lipids of lschemic and non-ischemic

ventricular lo IHA

myocardium.

Adult

male Wistar

rats were exposed

hypoxia

of 7000 m in a barochamber for 8 h/da), 5 days/week. 5 weeks altogether. Control (normoxic) animals were kept at the altitude of 200 m. One day after the last exposure, the regional &hernia was induced in anesthetized open-chest animals by occlusion of the LAD coronary artq for 9 or 30 min. Phospholipids (PI.) and triacylglycerols (‘IX;) were separated by thin-layer chromatography and their f::\ composition was analyzed by gas chromatograph>. Chronic hypoxia increased the ratio of n-3/n-6 polyunsaturated F..I (PIJFA) in cardiac PI. and TCI: this effect was mainly due 10 ;i higher proportion of 22:6n-3. Acute ischemia of 9-min duration caused a further increase of this particular FA only in the chronically hypoxic myocardium. In contrast, 30-min

ischemia

raised

the proportion

of 20:4n-6

in cardiac

TG

of

both normoxic and hypoxic groups IflA hypoxia affect n-3 PIIF/\ but increased proportion of 20:4n-6 TG. It is supposed that elevated n-3/n-6 PI!FA

did not in serum ratlo in

membrane

lipids

ischemic

tolerance

of chronically

Supportedhy

may

MSMT

contribute hypoxic

to

improved

hearts.

1131 00001.

IDENTIFICATION OF GENES COMMONLY EXPRESSED IN BOTH CARDIAC A!! OXIDATIVE SKELETAL MUSCLES Lumme Kadaja, Ylo Puurand, Enn K. Seppet.. Dept. of Pat.hophysiology, ITniversity of Tartu, Estonia Recent data have suggested different mechanism of regulation of mitochondrial respiration in oxidative and glycolytic muscles in viva. This difference may be related to specific protein expression, which is restricted to cardiac and slow-twitch skeletal muscles. To reveal t.he nature of these proteins, we have developed a new PCR-based method, which allows to identify the genes that are expressed solely in the oxidative muscles. Shortly, the total R.h;A pools, isolated from the heart, m. soleus (oxidative) and m. extensor digitorum longus (FJL, glycolytic) of mouse were reverse-transcribed into cDNAs. By means of subtractive hybridization versus EDL two populations of cDNAs (2PcDNA) were obtained: one specific to heart and another specific t.0 m. soleus. Thereafter the common pooi of 2PcDNA was isolated directly by applying a novel and economical approach without prior analysis of both populations individually. The results show that the common cDNA formed a small fraction of 2PcDNA. Thus, we have isolated the set. of cDNAs for identification of genes

which

mitochondrial skeletal

might

be

function muscles.

involved

in

in

cardiac

a control

and

over

oxidative