Objective Check if the Temporal flow response to Tilt could provide early hemodynamic pattern in the minutes preceding a syncope during the Tilt test performed after a 60-d head down bedrest (HDBR). Method Twenty-one men divided into 3 groups [Control (Con), Resistive Vibration (RVE) and Chinese Herb (Herb)] underwent a 60 day HDBR. Pre and Post HDBR a 20 min Tilt identified Finishers (F) and Non Finishers (NF). Cerebral (MCA), Temporal (TEMP), Femoral (FEM) flow velocity, were measured by Doppler during the Tilt. Blood pressure (BP) was measured by arm cuff and cardiopress. Results and Discussion Four of the 21 subjects were NF at the post HDBR Tilt test (Con gr:2, RVE gr: 1, Herb gr: 1). At 1 min and 10 s before end of Tilt in NF gr, FEM flow decreased less and MCA decreased more at post HDBR Tilt compared to pre (p<0.05), while in the F gr they changed similarly as pre. In NF gr: TEMP flow decreased more at post HDBR Tilt compared to pre, but only at 10 s before the end of Tilt (P<0.05). During the last 10 s a negative TEMP diastolic component appeared which induced a drop in mean velocity until Tilt arrest. Conclusion The sudden drop in TEMP flow with onset of a negative diastolic flow preceding the decrease in MCA flow confirm that the TEMP vascular resistance respond more directly than the cerebral one to the cardiac output redistribution and that this response occur several seconds before syncope.
To study changes of extracellular signal-regulated kinase 1 and 2 (ERK1/2) in femoral arteries of tail-suspended rats and their effects on contractility.Microgravity was simulated by elevating the hindquarters of Wistar rats to produce hindlimb unweighting (HU). In the absence or presence of prazosin and PD98059 respectively, isometric tension of vessel rings from femoral arteries in response to norepinephrine (NE) was determined by in vitro perfusion technique; Basal total ERK1/2 level and phosphorylated ERK1/2 level stimulated by norepinephrine in the absence or presence of prazosin and PD98059 respectively were detected by Western blotting-enhanced chemically lightening system.The maximal contractile response to NE was significantly lower in femoral arterial rings from 14 day-HU rats as compared with those in control rats. PD98059 caused a marked inhibition of NE-induced maximum contractile response in both control and HU femoral arterial rings. Moreover, the effect of inhibition was more significant in control rats than that in HU rats. Prazosin caused a right shift of the concentration-response curves (CRCs) to NE in both control and HU rats, but no difference was found between the two groups for the PA2 of prazosin calculated by Schild analysis, which showed that the sensitivity of alpha1 adrenoceptor was not changed by HU. After 7d-recovery, the difference of contractile response of femoral arterial rings to NE between recovered group and control group was nonsignificant. Data from Western blotting showed that basal total ERK1/2 levels were elevated in femoral arterial rings from 14d-HU rats as compared with those in control rats, but the levels of basal and NE-stimulated phosphorylated ERK1/2 were higher in control as compared with HU rats. After 7d recovery, the basal total ERK1/2 level and phosphorylated ERK1/2 level were not different from control.Microgravity simulated by 14d-HU can induce abnormality of MAPK/ERK pathway, which may contribute to declined contractile response of femoral vessel rings to NE.
Objective To study DSA manifestations of coronary to pulmonary artery shunt, and to assess the effectiveness of embolization therapy.Materials and Methods DSA findings in 9 patients with coronary to pulmonary artery shunt, diagnosed with selective coronary angiography, were analyzed, and embolization therapy with polyvinyl alcohol particles and soft steel wire was made.Results Of 9 patients, 2 had larger shunt, which was embolized three times with polyvinyl alcohol particles and soft steel wire. After the procedures, selective angiography confirmed that the shunt was completely occluded.Conclusion Selective coronary arteriography is of first choice for diagnosing coronary to pulmonary artery shunts. Embolization is a safe and minimum invasive therapy, and it should be adopted in symptomatic patients with larger shunt.
Purpose The objective was to investigate autonomic control in groups of European and Chinese astronauts and to identify similarities and differences. Methods Beat-to-beat heart rate and finger blood pressure, brachial blood pressure, and respiratory frequency were measured from 10 astronauts (five European taking part in three different space missions and five Chinese astronauts taking part in two different space missions). Data recording was performed in the supine and standing positions at least 10 days before launch, and 1, 3, and 10 days after return. Cross-correlation analysis of heart rate and systolic pressure was used to assess cardiac baroreflex modulation. A fixed breathing protocol was performed to measure respiratory sinus arrhythmia and low-frequency power of systolic blood pressure variability. Results Although baseline cardiovascular parameters before spaceflight were similar in all astronauts in the supine position, a significant increase in sympathetic activity and a decrease in vagal modulation occurred in the European astronauts when standing; spaceflight resulted in a remarkable vagal decrease in European astronauts only. Similar baseline supine and standing values for heart rate, mean arterial pressure, and respiratory frequency were shown in both groups. Standing autonomic control was based on a balance of higher vagal and sympathetic modulation in European astronauts. Conclusion Post-spaceflight orthostatic tachycardia was observed in all European astronauts, whereas post-spaceflight orthostatic tachycardia was significantly reduced in Chinese astronauts. The basis for orthostatic intolerance is not apparent; however, many possibilities can be considered and need to be further investigated, such as genetic diversities between races, astronaut selection, training, and nutrition, etc.
Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that, in all nonfainters, there was a progressive increase in heart rate over the course of HDBR, which remained higher until 12 days of recovery. The mean arterial pressure gradually increased until day 56 of HDBR and returned to baseline after 12 days of recovery. Respiratory sinus arrhythmia and baroreflex sensitivity decreased during HDBR and remained suppressed until 12 days of recovery. Low-frequency power of systolic arterial pressure increased during HDBR and remained elevated during recovery. Three subjects fainted during the HUTT after HDBR, in which systemic vascular resistance did not increase and remained lower until syncope. None of the circulatory patterns significantly differed between the fainters and the nonfainters at any time point. In conclusion, our data indicate that the impaired orthostatic tolerance after HDBR could not be distinguished by estimation of normal hemodynamic and/or neurocardiac data.
To disclose the changes in pathophysiology of cardiovascular deconditioning (CVD) induced by tail-suspension (TS) and to explore the effects of NOS inhibitor on CVD in TS rats.-30 degrees tail suspended rats were used as the model to simulate the physiological effects of microgravity. Wistar rats were randomly arranged into: control group (CON), 7 d TS group (TS 7 d) and TS 7 d + NOS inhibitor group (TS 7 d + L-NAME). Then, all the rats were subjected to +90 degrees head-up tilt to simulate the physiological effects of orthostatic stress (SO) after 7 d tail-suspension, only that the TS 7d + L-NAME rats were injected with 10(-6) M L-NAME (N-nitro-L-arginine methylester) through hypoglossal vein before tilting after 7 d TS. Carotid pressure and limb II ECG were measured with a PowerLab physiological system during 120 min tilt, and mean arterial pressure (MAP) and heart rate (HR) were analysized.Only one transient episode of hypotension-bradycardia appeared during the tilt in CON rats, but seven episodes occurred in TS 7 d rats, while the TS 7 d + L-NAME rats has only a significant increase in MAP at 10 min. No differences were found between the other parameters in recumbent position and those during the tilt.The CVD in the rats induced by TS is relative to an increase of NO production. 10(-6) M L-NAME had an alleviating effects on the CVD, which might be due to the increase of peripheral resistance of blood vessels and the central sympathetic drive by the combination of L-NAME with NOS. The contribution of the perivascular nerves and pulmonary arteries to this effect remains to be further studied.
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