Blood viscosity and hematocrit in the estuarine crocodile, Crocodylus porosus

Abstract

Abstract1. Viscosities of whole blood and plasma from Crocodylus porosus were low in comparison with other diving animals when measured over a range of shear rates at 30°C (e.g. 2.89 ± 0.07 mPa.sec and 1.67 ± 0.06 mPa.sec respectively, at a shear rate of 450 sec-1). 2. Hematocrit (19.2 ± 0.5%) and mean cell hemoglobin concentration (262 ± 23 g/l) are high in crocodiles compared with non-diving reptiles. 3. Nucleation of the red blood cell does not seem to have affected viscosity. 4. The potential for oxygen transport was estimated from pooled blood reconstituted to a range of hematocrits and used to predict an optimal hematocrit of 38%, which greatly exceeded measured values. 5. Low blood viscosity is associated with low flow resistance and may assist circulation during the low blood pressure events occurring during diving.

Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands

“…However, little was known about longterm effects of prolonged exposure to hyperosmotic environments on the maintenance of osmotic homeostasis. All haematological values measured in this study for SW-acclimated animals were within the ranges reported for wild-caught C. porosus living in water bodies of varying salinities (Grigg, 1981;Wells et al, 1991), suggesting that SW-acclimated crocodiles were able to successfully maintain osmotic homeostasis despite extended exposure to hyperosmotic conditions. Moreover, extended exposure to hypersaline conditions appeared to have little long-term impact on the animal's growth, suggesting that the additional energy required in maintaining homeostasis was either relatively minimal or was compensated for by increased food intake (animals were fed ad libitum, so we cannot readily distinguish between these possibilities).…”

Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands

“…However, little was known about longterm effects of prolonged exposure to hyperosmotic environments on the maintenance of osmotic homeostasis. All haematological values measured in this study for SW-acclimated animals were within the ranges reported for wild-caught C. porosus living in water bodies of varying salinities (Grigg, 1981;Wells et al, 1991), suggesting that SW-acclimated crocodiles were able to successfully maintain osmotic homeostasis despite extended exposure to hyperosmotic conditions. Moreover, extended exposure to hypersaline conditions appeared to have little long-term impact on the animal's growth, suggesting that the additional energy required in maintaining homeostasis was either relatively minimal or was compensated for by increased food intake (animals were fed ad libitum, so we cannot readily distinguish between these possibilities).…”

How temperature influences the viscosity of hornworm hemolymph

“…Insect hemocytes may respond similarly to decreases in temperature, potentially explaining the steep incline in viscosity at low temperatures observed in the hemolymph of M. sexta larvae. The whole hemolymph viscosity values found here, irrespective of temperature, are similar in magnitude to values reported in other animals (Clarke and Nicol, 1993;Dunlap, 2006;Guard and Murrish, 1975;Macdonald and Wells, 1991;Palenske and Saunders, 2002;Wells et al, 1991). In most cases, direct comparisons cannot be made, because measurements have been conducted at different shear rates and temperature.…”

“…In most cases, direct comparisons cannot be made, because measurements have been conducted at different shear rates and temperature. When compared with the few viscosity measurements that have been made at the same shear rate (450 s −1 ) and temperature (30°C), the insect hemolymph viscosity (range=2.1-2.7 cP) is found to be close to that of both crocodiles (average=2.89 cP; Wells et al, 1991) and the western fence lizard (range=2.7-5.9 cP, with higher values at greater hematocrit; Dunlap, 2006). The differences are likely due to the percentage of cell mass within the blood, which is directly correlated with blood viscosity across species (Snyder, 1971;Woodcock, 1976).…”

“…The differences are likely due to the percentage of cell mass within the blood, which is directly correlated with blood viscosity across species (Snyder, 1971;Woodcock, 1976). The hematocrit percent of insect hemolymph is <5% (Clark and Jones, 1980), which is considerably less than the 18.7-50.8% measured in crocodiles and the western fence lizard (Dunlap, 2006;Wells et al, 1991). The removal of cell mass from blood to obtain plasma yields a lower viscosity in many organisms (Windberger et al, 2003), as is also seen here with insect whole hemolymph compared with plasma.…”

Allosteric Control of Oxygen Binding by Haemoglobin During Embryonic Development in the Crocodile Crocodylus Porosus: The Role of Red Cell Organic Phosphates and Carbon Dioxide

“…2). These results imply a steady increase in mean corpuscular haemoglobin concentration during embryonic life to 19 the values seen in juveniles (262±72 gl Ϫ1 , S.D., N=10) and a decrease in blood viscosity without compromising oxygen transport capacity (Wells et al 1991).…”

Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands

“…However, little was known about longterm effects of prolonged exposure to hyperosmotic environments on the maintenance of osmotic homeostasis. All haematological values measured in this study for SW-acclimated animals were within the ranges reported for wild-caught C. porosus living in water bodies of varying salinities (Grigg, 1981;Wells et al, 1991), suggesting that SW-acclimated crocodiles were able to successfully maintain osmotic homeostasis despite extended exposure to hyperosmotic conditions. Moreover, extended exposure to hypersaline conditions appeared to have little long-term impact on the animal's growth, suggesting that the additional energy required in maintaining homeostasis was either relatively minimal or was compensated for by increased food intake (animals were fed ad libitum, so we cannot readily distinguish between these possibilities).…”

How temperature influences the viscosity of hornworm hemolymph

“…Insect hemocytes may respond similarly to decreases in temperature, potentially explaining the steep incline in viscosity at low temperatures observed in the hemolymph of M. sexta larvae. The whole hemolymph viscosity values found here, irrespective of temperature, are similar in magnitude to values reported in other animals (Clarke and Nicol, 1993;Dunlap, 2006;Guard and Murrish, 1975;Macdonald and Wells, 1991;Palenske and Saunders, 2002;Wells et al, 1991). In most cases, direct comparisons cannot be made, because measurements have been conducted at different shear rates and temperature.…”

“…In most cases, direct comparisons cannot be made, because measurements have been conducted at different shear rates and temperature. When compared with the few viscosity measurements that have been made at the same shear rate (450 s −1 ) and temperature (30°C), the insect hemolymph viscosity (range=2.1-2.7 cP) is found to be close to that of both crocodiles (average=2.89 cP; Wells et al, 1991) and the western fence lizard (range=2.7-5.9 cP, with higher values at greater hematocrit; Dunlap, 2006). The differences are likely due to the percentage of cell mass within the blood, which is directly correlated with blood viscosity across species (Snyder, 1971;Woodcock, 1976).…”

“…The differences are likely due to the percentage of cell mass within the blood, which is directly correlated with blood viscosity across species (Snyder, 1971;Woodcock, 1976). The hematocrit percent of insect hemolymph is <5% (Clark and Jones, 1980), which is considerably less than the 18.7-50.8% measured in crocodiles and the western fence lizard (Dunlap, 2006;Wells et al, 1991). The removal of cell mass from blood to obtain plasma yields a lower viscosity in many organisms (Windberger et al, 2003), as is also seen here with insect whole hemolymph compared with plasma.…”

Allosteric Control of Oxygen Binding by Haemoglobin During Embryonic Development in the Crocodile Crocodylus Porosus: The Role of Red Cell Organic Phosphates and Carbon Dioxide

“…2). These results imply a steady increase in mean corpuscular haemoglobin concentration during embryonic life to 19 the values seen in juveniles (262±72 gl Ϫ1 , S.D., N=10) and a decrease in blood viscosity without compromising oxygen transport capacity (Wells et al 1991).…”

Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands

“…However, little was known about longterm effects of prolonged exposure to hyperosmotic environments on the maintenance of osmotic homeostasis. All haematological values measured in this study for SW-acclimated animals were within the ranges reported for wild-caught C. porosus living in water bodies of varying salinities (Grigg, 1981;Wells et al, 1991), suggesting that SW-acclimated crocodiles were able to successfully maintain osmotic homeostasis despite extended exposure to hyperosmotic conditions. Moreover, extended exposure to hypersaline conditions appeared to have little long-term impact on the animal's growth, suggesting that the additional energy required in maintaining homeostasis was either relatively minimal or was compensated for by increased food intake (animals were fed ad libitum, so we cannot readily distinguish between these possibilities).…”

How temperature influences the viscosity of hornworm hemolymph

“…Insect hemocytes may respond similarly to decreases in temperature, potentially explaining the steep incline in viscosity at low temperatures observed in the hemolymph of M. sexta larvae. The whole hemolymph viscosity values found here, irrespective of temperature, are similar in magnitude to values reported in other animals (Clarke and Nicol, 1993;Dunlap, 2006;Guard and Murrish, 1975;Macdonald and Wells, 1991;Palenske and Saunders, 2002;Wells et al, 1991). In most cases, direct comparisons cannot be made, because measurements have been conducted at different shear rates and temperature.…”

“…In most cases, direct comparisons cannot be made, because measurements have been conducted at different shear rates and temperature. When compared with the few viscosity measurements that have been made at the same shear rate (450 s −1 ) and temperature (30°C), the insect hemolymph viscosity (range=2.1-2.7 cP) is found to be close to that of both crocodiles (average=2.89 cP; Wells et al, 1991) and the western fence lizard (range=2.7-5.9 cP, with higher values at greater hematocrit; Dunlap, 2006). The differences are likely due to the percentage of cell mass within the blood, which is directly correlated with blood viscosity across species (Snyder, 1971;Woodcock, 1976).…”

“…The differences are likely due to the percentage of cell mass within the blood, which is directly correlated with blood viscosity across species (Snyder, 1971;Woodcock, 1976). The hematocrit percent of insect hemolymph is <5% (Clark and Jones, 1980), which is considerably less than the 18.7-50.8% measured in crocodiles and the western fence lizard (Dunlap, 2006;Wells et al, 1991). The removal of cell mass from blood to obtain plasma yields a lower viscosity in many organisms (Windberger et al, 2003), as is also seen here with insect whole hemolymph compared with plasma.…”

Allosteric Control of Oxygen Binding by Haemoglobin During Embryonic Development in the Crocodile Crocodylus Porosus: The Role of Red Cell Organic Phosphates and Carbon Dioxide

“…2). These results imply a steady increase in mean corpuscular haemoglobin concentration during embryonic life to 19 the values seen in juveniles (262±72 gl Ϫ1 , S.D., N=10) and a decrease in blood viscosity without compromising oxygen transport capacity (Wells et al 1991).…”