ABSTRACT
AIM: To investigate the effect of chronic intermittent hypobaric hypoxia (CIHH) on the activity of adrenergic receptor(AR) in rabbit sino-atrial node (SAN) by intracellular recording.METHODS: New Zealand rabbits were randomly divided into three groups: control group (Con), 14 d CIHH treatment group (CIHH14) and 28 d CIHH treatment group (CIHH28). The CIHH rabbits were exposed to a simulated 5 000 m (oxygen 11.1%) hypobaric hypoxia in hypoxic chamber for 14 d or 28 d (6 h/d), respectively. SAN preparation was used and the transmembrane action potential was recorded by micropipettes. Isoproterenol hydrochloride (ISO, agonist of β-AR) and phenylephrine (PE, agonist of α_1-AR) at different concentrations (0.01, 0.1 and 1 μmol/L) were applied cumulatively to investigate the electrophysiological effect of the drugs on the rabbit SAN among Con, CIHH14 and CIHH28 groups, respectively. RESULTS: (1) CIHH didnt change the parameters of action potential of SAN recorded under basic condition. (2) ISO changed some parameters of AP significantly in a dose-dependent manner, including increases in the amplitude of AP (APA), maximal rate of depolarization (V_(max)), the velocity of diastolic (phase 4) depolarization (VDD), and rate of pacemaker firing (RPF). (3) The response of AP to ISO in CIHH rabbits was decreased significantly compared to that in Con animals. Under 1 μmol/L of ISO, the increases in VDD, RPF, APA and V_(max) in CIHH animals were smaller than those in Con animals (P<0.05). (4) No effect of PE (0.01, 0.1 and 1 μmol/L) on the parameters of action potential was observed. CONCLUSION: CIHH decreases the reactivity of β-AR, but has no effect on α_1-AR in SAN of rabbit.
ABSTRACT
Objective: To estimate the blood concentration of isoflurane with the inspired andexpired concentrations during laparoscopic surgery. Methods: 2 sections were divided in this experiment: section 1:23 adult patients (ASA I～II)were received abdominal surgeries,of whom,12 patients for non-laparoscopic surgeries and the others for laparoscopic surgeries. Central venous blood samples were collected for gas chromatography determination 20, 40, 60, 80 min after inhalating isoflurane . We could receive two different F value (the fraction of uptake of isoflurane)through the formula. Section 2: 27 patients were recruited for abdominal surgeries, 13 for laparoscopic surgeries and the others for non-laparoscopic surgeries. All of the processes were the same as the former. Then we confirm the results obtained from section1. Results: The F was 0.52 in the laparoscopic surgeries and 0.44 in the nonlaparoscopic surgeries. In the laparoscopic surgeries, the bias (MDPE) was 17% , accuracy (MDAPE)was 22.88% and the wobble was 11.7% .The correlation coefficient (r)was 0.83. In the nonlaparoscopic surgeries, the MDPE was 5.37% , the MDAPE was 16.02% , the wobble was 15.86% .The correlation coefficient was 0.90. Conclusion: The formula could be used in abdominal surgeries to evaluate the concentration of isoflurane according to the clinical standard of MDPE