What is the rat's pulse rate? - briefly
The typical heart rate of a laboratory rat lies between «300 and 500 beats per minute». Values rise during stress or exercise and fall under anesthesia.
What is the rat's pulse rate? - in detail
The heart rate of a laboratory rat typically ranges between 300 and 500 beats per minute (bpm) under normal, unstressed conditions. Values vary with several factors:
- Species and strain: Sprague‑Dawley, Wistar and other common strains exhibit similar ranges, but specific genetic lines may show slight deviations.
- Age: Neonates can exceed 600 bpm, while older adults tend toward the lower end of the range.
- Sex: Males often record marginally higher rates than females, though differences are modest.
- Body temperature: Each 1 °C increase raises the rate by approximately 10–15 bpm; hypothermia produces the opposite effect.
- Activity level: Awake, freely moving rats display higher rates than those restrained or anesthetized.
- Anesthetic agents: Isoflurane, ketamine‑xylazine and other drugs depress cardiac rhythm; recorded rates may fall to 150–250 bpm depending on dosage.
Measurement techniques include:
- Electrocardiography (ECG) with sub‑cutaneous electrodes; provides precise waveforms and accurate bpm calculation.
- Photoplethysmography using infrared sensors placed on the tail or paw; suitable for non‑invasive, continuous monitoring.
- Pulse oximetry probes adapted for small rodents; yields simultaneous oxygen saturation and pulse rate.
- Direct arterial catheterization; offers invasive, high‑resolution data for research requiring arterial pressure correlation.
Calibration of equipment is essential. Verify sensor sensitivity with a known reference signal before each session. Record ambient temperature and ensure the animal’s core temperature remains within the physiological range (≈37–38 °C) to avoid confounding influences.
When reporting results, present the mean value, standard deviation, and the conditions under which measurements were taken. For example: «Mean heart rate = 382 ± 24 bpm, recorded in conscious, freely moving adult male Sprague‑Dawley rats at 37 °C».