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A simple and novel method to monitor breathing and heart rate in awake and urethane-anesthetized newborn rodents.

Zehendner CM, Luhmann HJ, Yang JW - PLoS ONE (2013)

Bottom Line: Rodents are most useful models to study physiological and pathophysiological processes in early development, because they are born in a relatively immature state.However, only few techniques are available to monitor non-invasively heart frequency and respiratory rate in neonatal rodents without restraining or hindering access to the animal.Here we describe experimental procedures that allow monitoring of heart frequency by electrocardiography (ECG) and breathing rate with a piezoelectric transducer (PZT) element without hindering access to the animal.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany. Zehendner@uni-mainz.de

ABSTRACT
Rodents are most useful models to study physiological and pathophysiological processes in early development, because they are born in a relatively immature state. However, only few techniques are available to monitor non-invasively heart frequency and respiratory rate in neonatal rodents without restraining or hindering access to the animal. Here we describe experimental procedures that allow monitoring of heart frequency by electrocardiography (ECG) and breathing rate with a piezoelectric transducer (PZT) element without hindering access to the animal. These techniques can be easily installed and are used in the present study in unrestrained awake and anesthetized neonatal C57/Bl6 mice and Wistar rats between postnatal day 0 and 7. In line with previous reports from awake rodents we demonstrate that heart rate in rats and mice increases during the first postnatal week. Respiratory frequency did not differ between both species, but heart rate was significantly higher in mice than in rats. Further our data indicate that urethane, an agent that is widely used for anesthesia, induces a hypoventilation in neonates whilst heart rate remains unaffected at a dose of 1 g per kg body weight. Of note, hypoventilation induced by urethane was not detected in rats at postnatal 0/1. To verify the detected hypoventilation we performed blood gas analyses. We detected a respiratory acidosis reflected by a lower pH and elevated level in CO2 tension (pCO2) in both species upon urethane treatment. Furthermore we found that metabolism of urethane is different in P0/1 mice and rats and between P0/1 and P6/7 in both species. Our findings underline the usefulness of monitoring basic cardio-respiratory parameters in neonates during anesthesia. In addition our study gives information on developmental changes in heart and breathing frequency in newborn mice and rats and the effects of urethane in both species during the first postnatal week.

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Differences of urethane metabolism in mice and rats within the first postnatal week.In P0/1 mice ethanol concentrations in blood plasma 60 minutes after urethane administration were significantly higher than in P0/1 rats. Ethanol in plasma from P6/7 rodents was not detected. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. ***P<0.001.
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pone-0062628-g005: Differences of urethane metabolism in mice and rats within the first postnatal week.In P0/1 mice ethanol concentrations in blood plasma 60 minutes after urethane administration were significantly higher than in P0/1 rats. Ethanol in plasma from P6/7 rodents was not detected. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. ***P<0.001.

Mentions: To elucidate if urethane metabolism differs between P0/1 and P6/7 we determined one of the major metabolites of urethane, ethanol [17], in blood plasma probes 60 minutes after urethane treatment. Ethanol concentration in P0/1 mice was significantly higher than in P0/1 rats (mice P0/1 9.5±1.43 µmol/l vs. P0/1 rats 0.84±0.99 µmol/l, n = 4 animals per group, P<0.001, Figure 5). Ethanol in plasma probes was not detectable at P6/7 in mice and rats (n = 4 animals per group).


A simple and novel method to monitor breathing and heart rate in awake and urethane-anesthetized newborn rodents.

Zehendner CM, Luhmann HJ, Yang JW - PLoS ONE (2013)

Differences of urethane metabolism in mice and rats within the first postnatal week.In P0/1 mice ethanol concentrations in blood plasma 60 minutes after urethane administration were significantly higher than in P0/1 rats. Ethanol in plasma from P6/7 rodents was not detected. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. ***P<0.001.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643944&req=5

pone-0062628-g005: Differences of urethane metabolism in mice and rats within the first postnatal week.In P0/1 mice ethanol concentrations in blood plasma 60 minutes after urethane administration were significantly higher than in P0/1 rats. Ethanol in plasma from P6/7 rodents was not detected. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. ***P<0.001.
Mentions: To elucidate if urethane metabolism differs between P0/1 and P6/7 we determined one of the major metabolites of urethane, ethanol [17], in blood plasma probes 60 minutes after urethane treatment. Ethanol concentration in P0/1 mice was significantly higher than in P0/1 rats (mice P0/1 9.5±1.43 µmol/l vs. P0/1 rats 0.84±0.99 µmol/l, n = 4 animals per group, P<0.001, Figure 5). Ethanol in plasma probes was not detectable at P6/7 in mice and rats (n = 4 animals per group).

Bottom Line: Rodents are most useful models to study physiological and pathophysiological processes in early development, because they are born in a relatively immature state.However, only few techniques are available to monitor non-invasively heart frequency and respiratory rate in neonatal rodents without restraining or hindering access to the animal.Here we describe experimental procedures that allow monitoring of heart frequency by electrocardiography (ECG) and breathing rate with a piezoelectric transducer (PZT) element without hindering access to the animal.

View Article: PubMed Central - PubMed

Affiliation: Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany. Zehendner@uni-mainz.de

ABSTRACT
Rodents are most useful models to study physiological and pathophysiological processes in early development, because they are born in a relatively immature state. However, only few techniques are available to monitor non-invasively heart frequency and respiratory rate in neonatal rodents without restraining or hindering access to the animal. Here we describe experimental procedures that allow monitoring of heart frequency by electrocardiography (ECG) and breathing rate with a piezoelectric transducer (PZT) element without hindering access to the animal. These techniques can be easily installed and are used in the present study in unrestrained awake and anesthetized neonatal C57/Bl6 mice and Wistar rats between postnatal day 0 and 7. In line with previous reports from awake rodents we demonstrate that heart rate in rats and mice increases during the first postnatal week. Respiratory frequency did not differ between both species, but heart rate was significantly higher in mice than in rats. Further our data indicate that urethane, an agent that is widely used for anesthesia, induces a hypoventilation in neonates whilst heart rate remains unaffected at a dose of 1 g per kg body weight. Of note, hypoventilation induced by urethane was not detected in rats at postnatal 0/1. To verify the detected hypoventilation we performed blood gas analyses. We detected a respiratory acidosis reflected by a lower pH and elevated level in CO2 tension (pCO2) in both species upon urethane treatment. Furthermore we found that metabolism of urethane is different in P0/1 mice and rats and between P0/1 and P6/7 in both species. Our findings underline the usefulness of monitoring basic cardio-respiratory parameters in neonates during anesthesia. In addition our study gives information on developmental changes in heart and breathing frequency in newborn mice and rats and the effects of urethane in both species during the first postnatal week.

Show MeSH
Related in: MedlinePlus