Ps100

Blood pressure and blood gases were measured in a separate cohort (n = 8/group) as previously described to confirm whether such an anesthesia regimen affects cardiorespiratory function. Briefly, arterial blood was sampled in the ISO or SEV rats via a 24-gauge arterial puncture needle (IntroCan®-W, Braun Medical Inc., Bethlehem, PA, USA) through the abdominal aorta using a dissecting microscope (PS100, Nikon, Tokyo, Japan). The mean arterial blood pressure (MAP) was measured by an anesthesia monitor (M3046, Philips Medical System, Boeblingen, Germany). The blood sample (0.2-0.03 ml) was immediately analyzed to determine pH, arterial oxygen, and carbon dioxide using the blood gas analyzer (GEM Premier 3000, Bedford, MA, USA).

Arterial blood (0.3 ml) was sampled from three rats in each group of the four anesthetized groups via inserting 24-gauge polyethylene catheters (IntroCan®-W, B/Braun) through the abdominal aorta. Insertion was conducted using a dissecting microscope (PS100, Nikon, Tokyo, Japan). Rats in the mechanical ventilation groups were ventilated constantly to insure proper anesthesia depth when exposing the abdominal aorta. In the spontaneously breathing groups, the membrane sealed hole was opened and the rats body was pulled outside the chamber for arterial blood pressure monitoring and blood gas analysis. The rats head was kept within the chamber throughout the procedure, and the voids around the head were sealed with a membrane. Mean arterial blood pressure (MAP) was detected with a measuring instrument (M3046A, Philips, Boeblingen, Germany). Blood samples were immediately analyzed to determine pH, arterial oxygen, carbon dioxide and blood glucose values (GEM Premier 3000, Bedford, MA, USA). Rats in the control group were anesthetized with ketamine for blood gas measurement (10 mg⋅kg⁻¹, i.p. injection; Fujian, China, n = 3).