Summary
Young (7 weeks) spontaneously hypertensive rats (SHR) were kept on food-restriction (33%) during 4 weeks with (0.3% saline as drinking water) or without sodium supplementation. Body weight and indirect systolic blood pressure (tail plethysmography) were followed each weak. During the last week of the intervention period 24 hour excretions of sodium, dopamine and nor-adrenaline were measured. Vascular pressor responses to noradrenaline were evaluated in pithed rats and the sympathetic nerve activity was assessed from the disappearance of endogenous noradrenline in the heart after synthesis inhibition. Despite a clear retardation of the growth rate in food-restricted rats the development of hypertension was not influenced. Food-restriction was associated with a moderate suppression of sympathetic activity. Furthermore, the vascular pressor responses to noradrenaline were decreased but this was reversed following sodium supplementation. It is concluded that despite evidence of sympathetic suppression weight reduction does not reduce the blood pressure in SHR once the blood pressure has started to rise.
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References
Andén NE, Fuxe K, Hamberger B, Hökfelt T (1966) A quantative study of the nigrostriatal dopamine neuron system in the rat. Acta Physiol Scand 67: 306–312
Bunag RD (1983) Facts and fallacies about blood pressure in rats. Clin Exp Hypertens A5: 1659–1681
Dahl LK, Silver L, Christie RW (1958) The role of salt in the fall of blood pressure accompanying reduction in obesity. N Engl J Med 258: 1186–1192
DiNicolantiano R, Mendelsohn FAO, Hutchingson JS (1983) Sodium chloride preference of genetically hypertensive and normotensive rats. Am J Physiol 245: R38–44
Drew GM (1976) Effects of a-adrenoceptor agonists and antagonists on the pre- and postsynaptically located α-adrenoreceptors. Eur J Pharmacol 36: 313–320
Fagerberg B, Andersson O, Persson B, Hedner T (1985) Reactivity to norepinephrine and effect of sodium on the blood pressure during weight loss. Hypertension 7: 586–592
Felice LJ, Felice JD, Kissinger PT (1978) Determination of catecholamines in rat brain parts by a reversed phase ion-pair liquid chromatography. J Neurochem 31: 1461–1465
Fernandes G, Rozek M, Troger D (1986) Reduction of blood pressure and restoration of T-cell immune function in spontaneously hypertensive rats by food restriction and/or by treadmill exercise. J Hpyertens 4 [Suppl 3]: 469–474
Folkow B, Ely DL (1987) Dietary sodium effects on cardiovascular and sympathetic neuroeffector functions as studied in various rat models. J Hypertens 5: 388–395
Fröhlich ED (1986) Is the spontaneously hypertensive rat a model for human hypertension? J Hypertens 4 [Suppl 3]: 15–19
Gillespie JS, Muir TC (1967) A method of stimulating the complete sympathetic outflow from the spinal cord to blood vessels in the pithed rat. Br J Pharmacol Chemother 30: 78–87
Gradin K, Nissbrant H, Ehrenström F, Henning M, Persson B (1988) Adrenergic mechanisms during hypertension induced by sucrose and/or sodium in the spontaneously hypertensive rat. Naunyn-Schmiedebergs Arch Pharmacol 337: 47–52
Gradin K, Dahlöf C, Persson B (1986) A low dietary sodium intake reduces the neuronal noradrenaline release and the blood pressure in spontaneously hypertensive rats. Naunyn-Schmiedebergs Arch Pharmacol 332: 364–369
Haynes RB, Harper AC, Costley SR, Johnston M, Logan AG, Flanagan PT, Sacket! DL (1984) Failure of weight reduction to reduce mildly elevated blood pressure: a randomized trial. J Hypertens 2: 535–539
Henry DP, Dentino M, Gibbs PS, Weinberger MH (1979) Vascular compartmentalization of plasma norepinephrine in normal man. The relationship between venous and arterial norepinephrine concentration and the urinary excretion of norepinephrine. J Lab Clin Med 94: 429–437
Preuss M, Preuss HG (1980) The effect of sucrose and sodium on blood pressure in various substrains of Wistar rats. Lab Invest 43: 101–107
Spector S, Sjoerdsma A, Udenfriend S (1965) Blockade of endogenous norepinephrine synthesis by α-methyl-tyrosine, an inhibitor of tyrosine hydroxylase. J Pharmacol Exp Ther 147: 86–95
Tipton CM, Matthes RD, Rawlett KA, Leininger JR (1983) Influence of exercise intensity, age and medication on resting blood pressure of SHR populations. J Appl Physiol 55 (4): 1305–1310
Trolin G (1975) Involvement of α-adrenergic receptors at different levels of the central nervous system in the regulation of blood pressure and heart rate. Acta Physiol Scand [Suppl430]
Wright GL, McMurty JP, Wexler BC (1981) Food restriction reduces the blood pressure of the spontaneously hypertensive rat. Life Sci 28: 1253–1259
Young JB, Landsberg L (1977) Suppression of the sympathetic nervous system during fasting. Science 196: 1473–1475
Young JB, Muller D, Landsberg L (1978) Caloric restriction lowers blood pressure in the spontaneously hypertensive rat. Metab Clin Exp 27: 1711–1714
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Gradin, K., Persson, B. Blood pressure and sympathetic activity in spontaneously hypertensive rats during food restriction. J. Neural Transmission 79, 183–191 (1990). https://doi.org/10.1007/BF01245129
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DOI: https://doi.org/10.1007/BF01245129