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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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Developmental changes in respiratory and heart rate during the first postnatal week.In rats and mice breathing frequency significantly increased during the first postnatal week (A). We did not observe differences in RPM at corresponding ages between mice and rats. Heart rate increased from P0/1 to P6/7 in both species (B). Note that mice have significantly faster heart frequencies than rats at the same age. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. *P<0.05, **P<0.01, ***P<0.001.
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pone-0062628-g002: Developmental changes in respiratory and heart rate during the first postnatal week.In rats and mice breathing frequency significantly increased during the first postnatal week (A). We did not observe differences in RPM at corresponding ages between mice and rats. Heart rate increased from P0/1 to P6/7 in both species (B). Note that mice have significantly faster heart frequencies than rats at the same age. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. *P<0.05, **P<0.01, ***P<0.001.

Mentions: To determine developmental changes in awake unrestrained mice and rats in cardio-respiratory physiology during the first neonatal week, we evaluated heart and breathing rate at postnatal day 0/1 (P0/1) and at P6/7. Breathing and heart rate increased significantly within the first 7 postnatal days in both species. Respiration rate in P0/1 rats was significantly lower compared to P6/7 (rats P0/1∶144±39 respirations per minute (RPM) vs. rats P6/7∶232±30 RPM at P6/7, n = 5–7 animals, P<0.01, Figure 2A). In mice we obtained similar data (mice P0/1∶140±38 RPM vs. mice P6/7∶270±26 RPM, n = 5–6 animals, P<0.001, Figure 2A). No significant differences in RPM were noted between rats and mice of the same age.


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)

Developmental changes in respiratory and heart rate during the first postnatal week.In rats and mice breathing frequency significantly increased during the first postnatal week (A). We did not observe differences in RPM at corresponding ages between mice and rats. Heart rate increased from P0/1 to P6/7 in both species (B). Note that mice have significantly faster heart frequencies than rats at the same age. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. *P<0.05, **P<0.01, ***P<0.001.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0062628-g002: Developmental changes in respiratory and heart rate during the first postnatal week.In rats and mice breathing frequency significantly increased during the first postnatal week (A). We did not observe differences in RPM at corresponding ages between mice and rats. Heart rate increased from P0/1 to P6/7 in both species (B). Note that mice have significantly faster heart frequencies than rats at the same age. Box and whisker plots (displaying 75th percentile, median and 25th percentile) are shown, whiskers indicate minimum and maximum values. *P<0.05, **P<0.01, ***P<0.001.
Mentions: To determine developmental changes in awake unrestrained mice and rats in cardio-respiratory physiology during the first neonatal week, we evaluated heart and breathing rate at postnatal day 0/1 (P0/1) and at P6/7. Breathing and heart rate increased significantly within the first 7 postnatal days in both species. Respiration rate in P0/1 rats was significantly lower compared to P6/7 (rats P0/1∶144±39 respirations per minute (RPM) vs. rats P6/7∶232±30 RPM at P6/7, n = 5–7 animals, P<0.01, Figure 2A). In mice we obtained similar data (mice P0/1∶140±38 RPM vs. mice P6/7∶270±26 RPM, n = 5–6 animals, P<0.001, Figure 2A). No significant differences in RPM were noted between rats and mice of the same age.

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