AIM: To determine the effect of intermittent hypoxia (IH) precondition on ischemic myocardium by using a rabbit model of chro nic myocardial ischemia with left anterior descending (LAD) banding. METHODS: Male, adult New Zealand white rabbits were assigned into three groups randomly. (1) normal group (N group), (2) control group (C group), (3) IH precondition group (H group). A LAD band was placed in C and H group firs t. The rabbits in H group were exposed to altitude of 5 000 m, for 6 h/day c ontin uously. According to IH precondition duration, the animals were subdivided into 7-days group (H1) and 42-days group (H2). After these experiments, the mRNA conc entrations of vascular endothelial growth factor (VEGF), hypoxia induced factor (HIF-1?), endothelial nitric oxide synthase (eNOS) and the expression of VEGF p rotein were detected. Tissue sections were stained for alkaline phosphatase with indoxyl-tetrazolium method to detect capillary density. RESULTS: The mRNA levels of VEGF, HIF-1?, eNOS and expression V E GF protein were increased in H group significantly. Compared with C and N group, the capillary density in H group was increased significantly. CONCLUSION: IH precondition increases angiogenesis in chronic is chemic myocardium in rabbits.

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 didnt 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.

Objective:To explore the trend of postpartum hemorrhage after two-child policy and to analyze the high-risk risks of postpartum hemorrhage so as to put forward intervention measures to reduce the postpartum hemorrhage.Methods:We retrospectively selected 8 784 delivery women with routine production inspection and hospitalized at a ClassⅢ Grade A hospital from 2014 to 2018. We collected the general information, record of production inspection, delivery record and analyzed the trend of postpartum hemorrhage rate, blood loss and related high-risk factors.Results:From 2014 to 2018, there were statistical differences in the postpartum hemorrhage rate, serious postpartum hemorrhage rate and blood loss ( P<0.05) . The trend showed an increasing trend. In 2017, the postpartum hemorrhage rate, serious postpartum hemorrhage rate and blood loss were 16.9%, 6.1% and (540.1±758.2) ml respectively highest in those years. From 2014 to 2018, the percentage of delivery women with advanced ages, multiple pregnancy, pregnancy times≥2, history of cesarean section≥2 were increasing; delivery women with the prenatal hemoglobin≤110 g/L and percentage of natural labor were decreasing with a statistical difference ( P<0.05) ; the percentage of emergency cesarean section was on the rise; the percentage of placental expulsion time from 15 to 30 minutes declined with statistical differences ( P<0.05) ; the percentage of placental expulsion time≥30 minutes and above was no significant trend. Conclusions:From 2014 to 2018, the postpartum hemorrhage rate, serious postpartum hemorrhage rate and blood loss did not show an increasing trend. However, the percentage of high-risk pregnant and delivery women increased gradually. Therefore, we should carry out the pregnancy risk assessment rating for pregnant and delivery women and formulate a suitable high-risk assessment tool for postpartum hemorrhage so as to reduce the incidence of postpartum hemorrhage.