Effects of dopamine on total peripheral resistance and integrated systemic venous blood volume in dogs

Abstract

SunzmaryThe effect of dopamine on the peripheral circulation was investigated in 19 anaesthetized dogs with cardio-pulmonary bypass. Perfusion rate and both caval vein pressures were kept constant. Thus the peripheral effects could be studied in the absence of any direct or indirect influences from the heart. Dopamine was infused over a time span of 3 min in 61 experiments. In dogs with intact arterial pressoreceptors, doses of 25 and 50 ~g/kg effected a decrease in mean arterial pressure of up to 7 mmHg; doses of 100 and 200 ~g/kg effected initially a decrease and subsequently a dose-related increase in mean arterial pressure by up to 33 mmHg. Venous blood volume decreased by up to 4.2 ml/kg. In dogs with denervated arterial pressoreceptors, the arterial and venous effects were more pronounced. After beta receptor blockade, the initially effected decrease in mean arterial pressure was unchanged, whereas the subsequent increase in mean arterial pressure was significantly more pronounced.It is concluded that three components of action are involved in the effect of dopamine on the peripheral resistance vessels. Besides the well-known vasoconstriction mediated by alpha receptors, there are two vasodilating components, one of the two being mediated by beta receptors. Moreover, dopamine effects a constriction of the integrated systemic venous bed. When referred to the same increase in arterial pressure, the venous effect of dopamine is stronger than that of norepinephrine and as strong as that of epinephrine. The venoconstriction must lead to an increased venous return and hence to an increase in cardiac output and arterial pressure. The beneficial effect of dopamine in the treatment of shock appears to be due to the advantageous combination of these components of action.

Effects of fenoldopam on kidney function parameters and its therapeutic efficacy in the management of acute kidney injury in dogs with heatstroke

“…It has been studied as a substitute for dopamine, which failed to show beneficial effects in managing AKI in human patients . In the renal proximal tubule, DA‐1 receptor activation results in vasodilatation of the renal arteries, promoting natriuresis and diuresis, increasing renal blood flow, and therefore, fenoldopam is considered part of the management of AKI in human patients …”

“…11,13 In the renal proximal tubule, DA-1 receptor activation results in vasodilatation of the renal arteries, promoting natriuresis and diuresis, increasing renal blood flow, and therefore, fenoldopam is considered part of the management of AKI in human patients. [34][35][36][37] Fenoldopam may increase UP by increasing both natriuresis and GFR. 38 In our study, UP was high at presentation (Figure 1), with no significant difference between the study and the placebo groups, suggesting that the effect of fenoldopam on UP was mild at best.…”

Effect of Fenoldopam Continuous Infusion on Glomerular Filtration Rate and Fractional Excretion of Sodium in Healthy Dogs

“…The increase in GFR after fenoldopam likely occurred as a result of increased renal plasma flow (RPF). At effective doses, activation of DA‐1 receptors in the renal arteries and arterioles has been shown to cause renal vasodilatation and increased RBF in humans, dogs, and rats . This effect is proposed to cause a subsequent increase in GFR.…”

“…At effective doses, activation of DA-1 receptors in the renal arteries and arterioles has been shown to cause renal vasodilatation and increased RBF in humans, dogs, and rats. 3,5,[12][13][14] This effect is proposed to cause a subsequent increase in GFR. However, the increased RPF seen in humans has failed to consistently result in increased GFR, and studies in dogs have shown similarly variable results.…”

Preliminary pharmacokinetics and cardiovascular effects of fenoldopam continuous rate infusion in six healthy dogs

“…In systemic circulation, the activation of the DA‐1 receptor on smooth muscle causes vasodilation. In kidney, the activation of DA‐1 receptors in the renal proximal tubule causes renal vasodilation, promotes natriuresis and diuresis, increases renal blood flow, and preserves or improves glomerular filtration rate (Grund et al. , 1979; Goldberg, 1988).…”