Erythropoietin in the cerebrospinal fluid of patients with aneurysmal subarachnoid haemorrhage originates from the brain.

Recent years' research has revealed a specific, neuroprotective erythropoietin (EPO) system in the central nervous system (CNS) that is upregulated by hypoxia. The presence and dynamics of EPO in the cerebrospinal fluid (CSF) of patients with subarachnoid haemorrhage (SAH) has not been investigated. We collected a total of 83 corresponding serum and CSF samples from 18 patients with aneurysmal SAH and compared the concentrations of EPO with those of blood-derived markers of blood-brain barrier function (albumin, transferrin, alpha(2)-macroglobulin) and with those of proteins with well-known CNS synthesis (prealbumin, apolipoprotein E).

Sympathetic control of hemodynamics during moderate head-up tilt in human subjects.

To confirm sympathetic control of hemodynamics during postural change, sympathetic nerve activity supplying the anterior tibial muscle (MSNA) was measured by microneurography and muscle blood flow (MBF) by the xenon washout method during graded head-up tilt from 0 degrees horizontal to 30 degrees in 5 degrees increments. MSNA was represented as the increase in burst rate with increased tilt angle. The increments of MSNA from 0 degree horizontal were statistically significant at all tilt angles.

Central venous pressure in humans during microgravity.

Based on the results of head-down simulation studies and the results of parabolic flights, the hypothesis was tested that central venous pressure (CVP) in humans increases during microgravity (weightlessness) compared with during the ground-based supine position. CVP was recorded with an intravascular pressure transducer in seven healthy humans during short (20-s) periods of microgravity created by parabolic-flight maneuvers and in one astronaut before, during, and up to 3 h after launch of the Spacelab D-2 mission (Space Transport System-55). When the subjects were supine during the parabolic maneuver, CVP decreased during microgravity from 6.

Relative role of low- and high pressure reflexes on sympathetic activity in humans during simulated gravitational stress.

In order to determine the relative role of low- and high-pressure reflexes, respectively, on forearm sympathetic nerve activity (fSNA), 10 normal male subjects underwent a 4-step (5 min each) graded lower body negative pressure (LBNP) from -10 to -50 mmHg. Central venous pressure (CVP) and stroke volume gradually decreased (p<0.05), and arterial pulse pressure (PP) abruptly decreased at LBNP of -50 mmHg.

Volume-homeostatic mechanisms in humans during a 12-h posture change.

On one day six male subjects underwent an upright seated (SEAT) study, and on another day they were subjected to a head-down tilt of 3 degrees (HDT). Compared with SEAT, HDT induced prompt increases in central venous pressure (CVP) from -0.5 +/- 0.