[Restoration of the heart activity in deep hypothermia with the aid of norepinephrine and no warming of the heart].
A possibility of restoration and stimulation of the rat isolated heart contractions in deep hypothermia by means of norepinephrine (6 microM) was studied. Following a complete arrest of the heart at a retrograde perfusion with the Krebs-Henseleit buffer ([K+] 5.9 mM), norepinephrine was found to restore the heart beats and to lower the heart arrest temperature from 8.2 +/- 0.5 degrees to 6.6 +/- 0.3 degrees. At the perfusion with the Krebs-Henseleit buffer, the heart rate dropped to below 10 min(-1) at 13.0 +/- 0.9 degrees. Reduction of [K+] to 2.95 mM intensified the heart rate. At a progressing cooling, the heart rate lower than 10 min(-1) occurred at 10.9 +/- 0.6 degrees. When adding norepinephrine (6 microM) to the perfusion fluid with [K+] 2.95 mM, the heart rate increased once again (on the average to 23.1 +/- 5.3 min(-1)) despite the fact that the heart temperature continued to be lowered. The heart rate lower than 10 min(-1) was reached at the progressing cooling to, on the average, 9.6 +/- 0.7 degrees. The findings show norepinephrine to exert a stimulating effect on the heart activity even at such low heart temperatures as 7-10 degrees with no preliminary warming of the heart.
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Aliukhin
D000818:Animals; D003080:Cold Temperature; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006324:Heart Arrest, Induced; D006339:Heart Rate / Q000187:drug effects; D007036:Hypothermia, Induced; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats
D009638:Norepinephrine