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Biomedical subjects

L Röcker

Publications and source records attributed to L Röcker.

62 records · Page 4Linked to original sources
PubMed1976

Plasma volume, albumin and globulin concentrations and their intravascular masses. A comparative study in endurance athletes and sedentary subjects.

Plasma volume, hematocrit, intravascular protein concentration, colloid osmotic pressure and the intravascular mass of proteins were measured in 49 sedentary subjects and 40 endurance athletes (long-, middle distance runners, cyclists). The plasma volume in sedentary subjects was 42.7(35.8-51.7) ml/kg body weight (BW) as compared to 54.6(46.7-65.9) ml/kg BW in athletes. The protein concentrations were 71.0 (66.5-77.1) g/l in sedentary subjects and 69.0 (64.8-75.2) g/l in athletes. The respective numbers for the hematocrit were 44.6 (40.1-49.25)% and 42.8 (38.2-49.6)%, for the colloid osmotic pressure 38.0 (36.0-40.5) cm H2O (n=35) and 30.0 (25.0-34.4) cm H2O (n=31), for the intravascular mass of proteins 3.09 (2.45-4.01) g/kg BW and 3.75 (3.31-4.67) g/kg BW. All differences were statistically significant at least on the 5% level. The physiological consequences for athletes of having a lower hematocrit and lower protein concentration but a higher intravascular mass of proteins (+22%) for their waterbalance as well as for their dietary protein intake are discussed. Endurance exercise stimulates mainly the synthesis of albumin and globulins produced by the liver resulting in an expansion of the PV. The protein synthesis of the RES does not seem to respond to exercise stimulus.

Humans↗
PubMedDate not supplied

The cardiac filling pressure following exercise and thermal stress.

Under heat stress, a decrease of the central venous pressure (CVP) was regularly observed, raising the question of whether this reaction is a limiting factor for the circulation. In animal experiments it could be shown, however, that despite a lowered CVP, which depended on the elevated body temperatures, a high cardiac output (CO), as well as an elevated stroke volume could be maintained. A low CVP went hand in hand with a low total peripheral resistance. It was argued that under these circumstances the low CVP was not limiting because the intrinsic factors of the heart (sympathetic stimulation) were capable of maintaining a high CO. In human experiments the lowered CVP had to be seen in relation to the degree of dehydration. Regardless of whether the plasma volume remained constant, as in exercise, or declined, as in thermal stress (sauna), the CVP followed the volume depletion of the vascular and extravascular space, and it might well be that under these circumstances CVP is limiting. In this case, however, the altered CVP must be seen first as a monitor for the fluid deficit and not as a factor controlling cardiac function.

Adaptation, Physiological↗