Acid-Base Balance and Arterial Ion Concentrations in Rat Under Three Types of General Anaesthesia: Chronobiological Study

Abstract

The design and development of experimental, in vivo, chronobiological animal models may help reveal some of the relationships between circadian rhythms and biological functions. In vivo experiments require the use of appropriate anaesthesia, which should be selected according to their particular effect on the organism. The aim of study was to review the status of acid-base balance and ion concentration in arterial blood under common used general anaesthesias in experiments in dependence on the light-dark (LD) cycle in spontaneously breathing rats. The experiments were performed using three-to four-month-old pentobarbital (P)-, ketamine/xylazine (K/X)-and zoletil (Z)-aneasthetized female Wistar rats after a four-week adaptation to an LD cycle (12h light:12h dark). It was concluded that P anaesthesia disturbs LD dependence of acid-base balance compared to K/X and Z anaesthesia, but LD differences in plasma ion concentrations are disturbed under all type of general anaesthesia. P anaesthesia is not the most appropriate type of anaesthesia in rat chronobiological experiments. It eliminated LD differences, and also produces a more acidic environment, more pronounced hypercapnia and hypoxia than K/X and Z anaesthesias. This should be taken into account because the altered internal environment may affect the activity of systems whose functions are primarily dependent on acid-base balance or/and ion concentrations.

Ventilation via nose cone results in similar hemodynamic parameters and blood gas levels as endotracheal intubation during open chest surgery in rats

“…Hemodynamic parameters and blood gases were measured at baseline, during open chest and after closing of the chest. We found that hemodynamic features for MAP, HR and RPP were very similar between ventilation techniques and within physiological ranges 15 for both techniques of intubation (Figure 2 and Supplementary Table 1).…”

“…19 We have shown that using nose cone ventilation during anesthesia, it is possible to maintain: adequate blood circulation presented by heart rate, mean arterial pressure and rate pressure product; normal acid-base status as indicated by that pH, pCO 2 , HCO 3 and lactate that were within normal respective reference intervals; and normal oxygen uptake in the lungs assessed by pO 2 blood oxygenation. [15][16][17][18] The learning curve for this technique is shallow and no special instruments except the nose cone are necessary. Even with experience in endotracheal intubation technique, the nose cone ventilation is considerably easier to perform.…”

“…We have shown that using nose cone ventilation during anesthesia, it is possible to maintain: adequate blood circulation presented by heart rate, mean arterial pressure and rate pressure product; normal acid–base status as indicated by that pH, pCO 2 , HCO 3 – and lactate that were within normal respective reference intervals; and normal oxygen uptake in the lungs assessed by pO 2 blood oxygenation. 15–18…”

“…Therefore, a p ≤ 0.05, after adjusting for multiple testing, indicated that the parameters were ‘biologically’ equivalent for the different ventilation types. 15…”