Circadian course of PO2-oscillations in skeletal muscle of intact and portacaval shunted (PCA) rats.
In rats several circadian rhythms such as heart rate, body temperature, and locomotor activity are known. Several authors found a loss of day-night-rhythm (locomotor activity, EEG) after portacaval shunting (PCA). The aim of this study was to evaluate whether muscle PO2 oscillations are circadian and whether they are altered after time-limited hypercirculation caused by PCA. 126 days after operation tissue PO2 of m. rectus abdominis of 9 rats with PCA and 10 controls was measured with a multi-wire surface electrode. All animals were kept under constant conditions and each animal was measured 6 times at intervals of 4 hours in order to get a circadian PO2 course. In controls the circadian course of mean muscle PO2 resembled a sine oscillation with high values at night and low values in the afternoon. In PCA-rats the time course of mean muscle PO2 showed 3 oscillations with different amplitudes, each with a period length of 24 hours. Our results indicate that oscillations of muscle PO2 are determined principal by circadian locomotor activity and that time-limited hypercirculation influences the circadian course of mean muscle PO2.
Günderoth-Palmowski
M
M
Med. Univ. Klinik, Abtlg. I, Tübingen, FRG.
Heinrich
R
R
Palmowski
P
P
Dette
S
S
Daiss
W
W
Grauer
W
W
Egberts
E H
EH
D000818:Animals; D002940:Circadian Rhythm; D005260:Female; D009132:Muscles / Q000378:metabolism*; D010100:Oxygen / Q000032:analysis*; D010101:Oxygen Consumption; D010313:Partial Pressure; D011167:Portacaval Shunt, Surgical; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D010100:Oxygen