Animals were anesthetized with sodium pentobarbital (60 mg/kg, IP). The levels of anesthesia were maintained with a 20% solution (v/v) of the same anesthetic after assessing the withdrawal response. Rectal temperature was maintained through a homoeothermic blanket (Harvard Apparatus, Cambourne, UK). The trachea was cannulated below the larynx to record tracheal pressure. The femoral artery and vein were cannulated for blood pressure (BP) monitoring and injection of saline and drugs, respectively. The electrocardiogram (ECG) was recorded from subcutaneous electrodes placed into three limbs, and the heart rate was derived from the ECG recording (Neurology, Digitimer, Welwyn Garden City, UK).
The right carotid artery was cannulated, and chemoreceptors were stimulated by lobeline injection (0.2 mL, 25 µg/mL, Sigma, St. Louis, MO, USA). Baroreflexes were stimulated by phenylephrine injection (0.2 mL, 25 µg/mL, Sigma, St. Louis, MO, USA) in the femoral vein [29 (link),30 (link),31 (link)]. At the end of the above-mentioned acute experience, the animal was sacrificed with an overdose of anesthetic. The heart was then removed and placed in 4% paraformaldehyde (Sigma-Aldrich) at 4 °C for further histological studies.
The right carotid artery was cannulated, and chemoreceptors were stimulated by lobeline injection (0.2 mL, 25 µg/mL, Sigma, St. Louis, MO, USA). Baroreflexes were stimulated by phenylephrine injection (0.2 mL, 25 µg/mL, Sigma, St. Louis, MO, USA) in the femoral vein [29 (link),30 (link),31 (link)]. At the end of the above-mentioned acute experience, the animal was sacrificed with an overdose of anesthetic. The heart was then removed and placed in 4% paraformaldehyde (Sigma-Aldrich) at 4 °C for further histological studies.
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