Morphogenetic studies of the rabbit. XIX. Organ size in relation to body size in large race III and in small race X

The mechanism(s) of uptake of vitamin E (alpha-tocopherol) by tissues is poorly understood. It has, however, been suggested from studies in vitro that the apolipoprotein B/E (apo B/E) receptor pathway for low-density lipoprotein (LDL) may be involved. To investigate the role of the apo B/E receptor pathway in vivo, we have studied the transport and uptake of alpha-tocopherol by tissues in Watanabe Heritable Hyperlipidaemic (WHHL) rabbits, which lack functional LDL (apo B/E) receptors, and controls. [3H]alpha-Tocopherol incorporated within LDL labelled with [14C]sucrose was used in these studies, as this enabled the uptake of both alpha-tocopherol and LDL to be studied independently. The principal findings were as follows. (1) Concentrations of the circulating lipids (including alpha-tocopherol) and LDL were increased and the plasma fractional disappearance rates of alpha-tocopherol and LDL decreased in the WHHL rabbits. (2) The WHHL rabbits clear more LDL and alpha-tocopherol from the circulation than controls do, because of their increased pool sizes of alpha-tocopherol and LDL. (3) The lipoprotein composition of the WHHL rabbits differed from that of the controls, and there was exchange of alpha-tocopherol between the lipoprotein fractions in vivo and in vitro. (4) High-affinity apo B/E receptors were not essential for the uptake of alpha-tocopherol by tissues. (5) Evidence from the plasma-clearance and tissue data suggest that alpha-tocopherol can be taken up by tissues in association with, and also independent of, LDL. We conclude that there are several different mechanisms for the uptake of alpha-tocopherol by tissues, which include receptor-dependent and receptor-independent pathways, independent transport and co-transport of alpha-tocopherol and LDL, and uptake from a number of different lipoproteins.

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“…Total organ mass estimated by using tissue weights from the literature[21] as a function of total body weight.…”

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confidence: 99%

Plasma clearance and net uptake of α-tocopherol and low-density lipoprotein by tissues in WHHL and control rabbits

Cohn

Goss-Sampson²,

Grun

et al. 1992

Biochemical Journal

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“…The rabbit, on the other hand, has a very high resting heart rate, and the mean control heart rate of 273 beats/min seen in our experiments is quite close to the maximum possible for this species. Because the rabbit has the smallest heart weight in relation to body weight of any mammal (Latimer & Sawin, 1956;Poupa, Rakusan & Ostadal, 1970) the maximum stroke volume is obviously relatively small. The cardiac output reserve is therefore considerably smaller than that of the dog and the animals are probably using a greater proportion of their maximum heart rate and cardiac output capacity already at rest.…”

Section: Discussionmentioning

confidence: 99%

The Effect of a Xanthine Derivative, 1‐(5′oxohexyl)‐3‐methyl‐7‐propylxanthine (Hwa 285), on Heart Performance and Regional Blood Flow in Dogs and Rabbits

Hudlická

Komárek

Wright

1981

British J Pharmacology

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1 The effect of a new xanthine derivate 1-5' oxohexyl-3-methyl-7-proplyxanthine (HWA 285) was studied on heart performance in dogs and rabbits and on regional blood flow in rabbits. 2 Heart performance (cardiac output and dPldt max) in dogs was increased. Cardiac work (calculated as CO x mean BP) was not changed in dogs and did not change or was slightly decreased in rabbits. Heart rate was increased in dogs and unchanged in rabbits. 3 Blood pressure decreased slightly in dogs, and more markedly in rabbits. Total peripheral resistance was decreased in both species. 4 Regional blood flow (studied by use of 15 arm labelled microspheres) was increased in the heart, brain and skeletal muscle; the increase was dose-dependent in the range 0.3, 1.0 and 3.0 mg HWA 285 per kg intravenously. The highest dose produced a 2 fold decrease in the peripheral resistance in the brain, a 2.5 fold decrease in the heart and 4 fold decrease in skeletal muscle.5 The drugs preferentially dilated small (7 to 10 ,um) rather than larger (12 to 17 ,um) arterioles; 9 Am microspheres were found in the outflowing blood after application of the drug, and the calculated blood flow increases were smaller, or absent, as compared with values obtained with 15 ,um microspheres..

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Morphogenetic studies of the rabbit. XXXI. Weights and linear measurements of some of the bones of 65 race III rabbits

Latimer

Sawin

1962

Am. J. Anat.

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Morphogenetic studies of the rabbit. XIX. Organ size in relation to body size in large race III and in small race X

Cited by 30 publications

References 17 publications

Plasma clearance and net uptake of α-tocopherol and low-density lipoprotein by tissues in WHHL and control rabbits

Plasma clearance and net uptake of α-tocopherol and low-density lipoprotein by tissues in WHHL and control rabbits

The Effect of a Xanthine Derivative, 1‐(5′oxohexyl)‐3‐methyl‐7‐propylxanthine (Hwa 285), on Heart Performance and Regional Blood Flow in Dogs and Rabbits

Morphogenetic studies of the rabbit. XXXI. Weights and linear measurements of some of the bones of 65 race III rabbits

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