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At least 19 recordsLinked to original sources
PubMed1981

Measurement of red blood cell volume, plasma volume, and total blood volume in baboons.

Red blood cell volume was measured directly in baboons by infusion of 51Cr-labeled autologous RBC, and was indirectly estimated from the plasma volume measured with 125I-labeled albumin and the total body hematocrit. The total body hematocrit was calculated from the peripheral venous hematocrit multiplied by a correction factor; for nonanemic baboons the correction factor was 0.87, and for anemic baboons, 0.75. Within 2 weeks after the phlebotomy (150 ml of blood), the baboon's RBC volume was restored to normal. Posttransfusion survival of baboon RBC can be measured accurately in nonanemic baboons; the preserved RBC can be labeled with 51Cr and the RBC volume of the baboon can be measured indirectly from the plasma volume measured with 125I-labeled albumin and the total body hematocrit.

Animals↗
PubMed1978

The role of plasma volume, plasma renin and the sympathetic nervous system in the posture-induced decline in renal lithium clearance in man.

Excretion of lithium in urine was studied in 2 healthy males while recumbent and while upright, either walking or standing quietly. An oral dose of 24.3 mmol of Lit was taken as three lithium carbonate tablets 13 h before clearance tests. Renal lithium clearance decreased and lithium fractional reabsorption increased while upright. Standing immersed to the neck in water, which prevents the fall in plasma volume upon changing posture from recumbent to upright, prevented the fall in renal lithium clearance as well as the rise in lithium fractional reabsorption while upright. Oral doses of guanethidine (total dose of 200 mg) or oxprenolol (total dose of 140 mg) taken to prevent high levels of sympathetic nervous system activity and plasma renin, respectively, failed to prevent the fall in renal lithium clearance or the rise in lithium fractional reabsorption upon changing posture from recumbent to upright. The findings indicate that the fall in renal lithium clearance and the rise in lithium fractional reabsorption upon changing posture from recumbent to upright is related to the fall in plasma volume but not to high levels of sympathetic nervous system activity or plasma renin activity.

Absorption↗
PubMed1989

Influence of prolonged physical exercise on plasma volume, plasma proteins, electrolytes, and fluid-regulating hormones.

Fluid-regulating hormones [arginine vasopressin (AVP) and aldosterone] as well as electrolytes, plasma volume (PV), and plasma proteins were studied in 16 well-trained male amateur runners (mean age 31.8 years) before t0), immediately after (t1), and 60 min (t2) and 22 h (t3) after a marathon run. Immediately after the run PV was significantly decreased by 12.1%, whereas the concentration of plasma proteins increased by 13.9%, sodium by 5.8 mMol.l-1, and potassium by 0.58 mMol.l-1, respectively. Aldosterone increased by 1089 pg/ml and AVP by 9.0 pg/ml. PV was significantly increased 22 h after the run by 10.6% (P less than 0.001) and plasma proteins were increased by 1.0% (P greater than 0.05), whereas aldosterone and AVP as well as electrolytes returned to control values. At t1, and particularly at t2 and t3, the total plasma protein concentration increased much more than could have been expected from changes of PV. It is suggested that this phenomenon was caused by an influx of proteins into the vascular space. This might also be the reason for the expanded PV especially in the longer recovery period at t3. The volume-regulating hormones (AVP and aldosterone) may play an important role during and immediately after the run but not in the longer recovery period (t2 and t3).

Adolescent↗
PubMed1976

The relationship between total red cell volume, plasma volume and venous haematocrit.

Total red cell volume (TRCV) and plasma volume (PV) have been measured in 130 cases including 65 polycythaemic patients and 65 patients with a wide variety of disorders. Patients with gross splenomegaly were excluded from the study. The regression of TRCV on venous haematocrit (VHct) was found to be curvilinear, a single exponential function providing a good approximation ( r=0.92, P less than 0.001). No significant difference was found between the mean PVs of the polycythaemic and control groups (40.97 and 42.94 ml/kg respectively) although a slight but highly significant negative correlation was observed between PV and VHct (r = 0.47, P less than 0.001). This most marked for patients with VHcts below 0.30, for whom a separate plot yielded a correlation coefficient of 0.75. Total blood volume (TBV) and VHct were found to be positively correlated (r = 0.57, P less than 0.001) as would be expected from the TRCV and PV data. The significance of these findings is discussed.

Blood Volume↗
PubMed1981

Erythrocyte volume, plasma volume, and acid-base changes in exercise and heat dehydration.

Variations in erythrocyte volume [mean corpuscular volume (MCV)] were evaluated during exercise and heat stress to determine the influence on calculated plasma volume and content changes. The results of this study on 17 men indicate that the human red blood cell can increase, decrease, or remain constant in volume during physical stress depending on the combined interactions of plasma osmolality and blood pH. Shrinking of MCV can occur when the increase in plasma osmolality is larger than 5 mosmol/kg H2O and the blood pH remains within 0.1 pH units of its resting value. Erythrocyte swelling is usually noticed with maximal exercise when the blood pH is less than 7.10, in spite of 20 mosmol/kg H20 increments in plasma osmolality. The regression equations indicate that during 30 min of exercise in a cool environment the plasma shifts calculated by either the hematocrit or the hematocrit + hemoglobin method fall within 1% of each other, but during resting heat exposure the hematocrit technique under-estimates the fluid shift by 2.5-3.0%. Application of these considerations to the calculation of plasma content changes during stress made it clear that the pattern of plasma potassium content is quite different with maximal as compared with submaximal exercise.

Adult↗
PubMed1985

Interstitial fluid volume, plasma volume and transcapillary colloid osmotic gradient in patients with hepatic cirrhosis and fluid retention.

Colloid osmotic pressure in plasma (IIp) and in subcutaneous interstitial fluid (IIi) (wick technique), plasma volume (PV) and interstitial fluid volume (IFV) were measured in 12 patients with hepatic cirrhosis and fluid retention. The value of IIp (mean +/- SD) was 21.4 +/- 4.2 mmHg (28.6 +/- 3.4 mmHg in normal subjects (p less than 0.01)), mean IIi was 8.6 +/- 2.2 mmHg (15.8 +/- 2.7 mmHg in normal subjects (p less than 0.01)) and mean transcapillary colloid osmotic gradient (IIp-IIi) was 12.7 +/- 3.8 mmHg compared to 12.8 +/- 2.7 mmHg in normal subjects (p greater than 0.1). Mean PV was increased by 21% compared to normal values (p less than 0.01) and IFV increased by 43% (p less than 0.01). The study demonstrates that reduction in IIp in hepatic cirrhosis is accompanied by a decrease of IIi in subcutaneous tissue resulting in unchanged transcapillary colloid osmotic gradient. The reduction in IIi can partly be explained by simple dilution and partly by a decrease in interstitial protein mass. The wash-down of interstitial proteins in non-splanchnic tissues reduces the tendency to oedema and hypovolaemia.

Adult↗
PubMed1984

Interstitial fluid volume, plasma volume and colloid osmotic pressure in patients with nephrotic syndrome.

Colloid osmotic pressure in plasma (IIp) and in subcutaneous interstitial fluid (IIi) (wick technique), plasma volume (PV) and interstitial fluid volume (IFV) were measured in nephrotic patients (n = 11) and in healthy controls. Six of the patients were treated with ultrafiltration and the parameters were measured before and after withdrawal of mean 7460 ml (total ultrafiltrate in two sessions). In the nephrotic patients mean IIp was 11.6 mmHg and IIi was 3.9 mmHg compared to 28.6 mmHg and 15.8 mmHg, respectively, in healthy controls. PV was in the normal-to-high range and IFV was increased to 150% of the valued in controls. No statistically significant change in PV, IIp or IIi was found after ultrafiltration, and IFV was reduced by 20%. The results indicate that reduction in IIi is an important oedema-preventing factor and that the reduction in interstitial protein mass is more than proportional compared to the degree of hypoproteinaemia. Ultrafiltration in the rate and magnitude we have used, leads to reduction in IFV, but small changes in PV, IIp or IIi.

Adult↗
PubMed1990

Alterations in plasma volume, plasma constituents, renin activity and aldosterone induced by maximal exercise in the horse.

Plasma volume (PV) decreased by 13 per cent following the completion of 1,000 m of maximal exercise in the horse. This study demonstrated that the critical reduction in PV following maximal exercise occurred within 10 mins of completion of exercise, as previously reported in man. Total plasma protein (TPP) increased by 23 per cent at 2 and 5 mins, and by 21 per cent at 10 mins post exercise. Therefore, it does not appear to be an accurate measurement to assess the degree of PV contraction in the horse. Protein was apparently added to the intravascular space either during or following exercise. The changes in osmolality correlated strongly with those in sodium, which is the primary determinant of alterations in plasma tonicity. The increase in osmolality (12 per cent) was similar to the reduction in PV (13 per cent) concluding that a transient hypotonic fluid loss had occurred. The increase in plasma renin activity (PRA) following maximal exercise was followed by an increase in aldosterone (ALD) concentration in both magnitude and time course. Alterations in PV should be considered when interpreting electrolyte and serum enzyme activity data collected following maximal exercise.

Aldosterone↗
PubMed1998

Blood volume, plasma volume and circulation time in a high-energy-demand teleost, the yellowfin tuna (Thunnus albacares)

We measured red cell space with 51Cr-labeled red blood cells, and dextran space with 500 kDa fluorescein-isothiocyanate-labeled dextran (FITC-dextran), in two groups of yellowfin tuna (Thunnus albacares). Red cell space was 13.8+/-0.7 ml kg-1 (mean +/- s.e.m.) Assuming a whole-body hematocrit equal to the hematocrit measured at the ventral aortic sampling site and no significant sequestering of 51Cr-labeled red blood cells by the spleen, blood volume was 46. 7+/-2.2 ml kg-1. This is within the range reported for most other teleosts (30-70 ml kg-1), but well below that previously reported for albacore (Thunnus alalunga, 82-197 ml kg-1). Plasma volume within the primary circulatory system (calculated from the 51Cr-labeled red blood cell data) was 32.9+/-2.3 ml kg-1. Dextran space was 37.0+/-3.7 ml kg-1. Because 500 kDa FITC-dextran appeared to remain within the vascular space, these data imply that the volume of the secondary circulatory system of yellowfin tuna is small, and its exact volume is not measurable by our methods. Although blood volume is not exceptional, circulation time (blood volume/cardiac output) is clearly shorter in yellowfin tuna than in other active teleosts. In a 1 kg yellowfin tuna, circulation time is approximately 0.4 min (47 ml kg-1/115 ml min-1 kg-1) compared with 1. 3 min (46 ml kg-1/35 ml min-1 kg-1) in yellowtail (Seriola quinqueradiata) and 1.9 min (35 ml kg-1/18 ml min-1 kg-1) in rainbow trout (Oncorhynchus mykiss). In air-breathing vertebrates, high metabolic rates are necessarily correlated with short circulation times. Our data are the first to imply that a similar relationship occurs in fishes.

Journal Article↗