THE ACTION OF VASOPRESSIN, A VASOPRESSIN ANALOGUE (PLV2), OXYTOCIN, ANGIOTENSIN, BRADYKININ AND THEOPHYLLINE ETHYLENE DIAMINE ON RENAL BLOOD FLOW IN THE ANAESTHETIZED CAT

Effects and mechanism of action of aminophylline on cardiac function and regional blood flow distribution in conscious dogs

The effects of aminophylline, 1 mg/kg/min infused intravenously for 10 minutes, were examined on left ventricular (LV) diameter, pressure, an indexes of myocardial contractility, as well as systemic, coronary and regional hemodynamics in conscious dogs. Aminophylline increased mean arterial pressure 12 +/- 2%, LV systolic pressure 8 +/- 1%, LV dP/dt 20 +/- 2%, velocity of myocardial fiber shortening 13 +/- 2% and heart rate 5 +/- 2%, and reduced LV end-diastolic diameter 2 +/- 0.5%. Vascular resistance rose in the systemic bed 13 +/- 5%, the coronary bed 26 +/- 3%, the mesenteric bed 26 +/- 5% and the iliac bed 36 +/- 4%, but did not rise in the renal bed. Both beta-adrenergic receptor blockade with propranolol and chronic treatment with reserpine attentuated but did not abolish the positive inotropic response induced by aminophylline. Alpha-adrenergic receptor blockade with phentolamine prevented aminophylline-induced vasoconstriction in the systemic, coronary, mesenteric and iliac beds. In contrast to the vasoconstriction with i.v. aminophylline, when the drug was infused directly into the iliac artery, it elicited marked iliac vasodilation. Thus, in the intact conscious dog, i.v. aminophylline, in a dose that had little effect on heart rate, increased LV contractility and reduced preload. The increase in contractility was dependent in part on intact beta-adrenergic nervous activity and endogenous catecholamine stores. The increase in systemic, coronary, iliac and mesenteric resistances involved alpha-adrenergic mechanisms. These actions appear to involve autonomic mechanisms, because the only direct effect of aminophylline on the iliac artery was marked vasodilation.

Effects of vasopressin, noradrenalin and oxytocin on blood flow distribution in rat kidney with neoplasm

The arterial blood flow distribution between tumour and intact renal tissue was investigated in rats with transplanted sarcomas. Changes in tissue flow were measured by the microsphere tracer technique, and the redistributing effects on blood flow of vasopressin, noradrenalin and oxytocin was recorded. Bolus injections of vasopressin gave a transient decrease of intact tissue flow, not found in tumours. At increasing doses of vasopressin and in early tumour growth phase, the flow discriminating effect tended to vanish. Constant intravenous infusion of vasopressin gave similar reduction of flow in tumour and intact tissue. Selective administration into the renal artery reduced flow in intact tissue but produced ambiguous effects in tumour tissue. Noradrenalin produced less reduction of tumour flow as compared with intact tissue flow. Oxytocin increased tumour blood flow while no flow change occurred in intact tissue. Oxytocin thus appeared to produce the most favourable redistribution of flow within tumour kidneys for the prospect of conveying cytotoxic agents selectively to the tumour.

Effects of vasopressin in experimental nephroangiography

Nephroangiography was performed in 13 rabbits using eight-fold magnification with a 0.05 mm focus. After arginine vasopressin in doses of 0.01 to 1.0 IU the glomeruli were well demonstrated as well as the subcortial arteries and veins and the concentration of contrast medium in arteries and veins increased. At increasing doses of vasopressin the glomeruli were shut off to an increasing degree, beginning at the outer part of the cortex. At 1.0 IU only the juxtamedullary glomeruli functioned.

The effect of octapressin on renal and intrarenal blood flow in cirrhosis of the liver

The effect of octapressin (2-phenylalanine-8-lysine vasopressin) on renal and intrarenal blood flow was studied in 11 normotensive cirrhotic patients with abnormal renal perfusion. Renal haemodynamic changes were assessed with the (133)Xenon washout technique. Of the six patients given suppressor doses of octapressin intravenously renal blood flow improved in one only. A further three patients responded to the drug in a dose which increased the mean arterial pressure by 5 or more mm Hg. The increase in mean renal blood flow was accompanied by an improvement in renal cortical perfusion. In two patients renal blood flow decreased after the administration of octapressin. These findings, in conjunction with previous reports, suggest that octapressin will only consistently improve renal perfusion in cirrhotic subjects who are hypotensive and in whom the mean arterial blood pressure is raised by the drug, but do not exclude the possibility that octapressin may have a direct renal circulatory effect in some patients.

The dense bodies of human platelets. Origin of serotonin storage particles from platelet granules

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Systemic vasoconstrictor and renal vasodilator effects of PLV-2 (octapressin) in man

The systemic and renal hemodynamic effects of PLV-2 (octapressin) were studied in patients with hypotension or decompensated cirrhosis of the liver. Low doses (0.004 to 0.02 units/min) increased renal blood flow (indicator-dilution technique), reduced renal vascular resistance, and produced a slight increase in arterial pressure and systemic vascular resistance. Higher doses (0.1 to 0.5 units/min) produced a sharp increase in arterial pressure and systemic resistance while renal resistance increased moderately and renal blood flow usually was maintained above control levels. Renal fraction was increased at all dose levels. The increased renal blood flow was accompanied by more rapid intrarenal dye transit time and slight increase in renal extraction ratio of paraaminohippurate suggesting a rise in cortical blood flow. It is concluded that PLV-2 in small doses produces renal vasodilation and in larger doses preferential extra-renal vasoconstriction resulting in redistribution of blood flow to the kidney.