Congestive heart failure dopamine receptors

Dopamine and dobutamine are sometimes used to stimulate the heart in cases of acute or severe heart failure (see Chapter 20). Dopamine and dobutamine exert a fairly specific positive inotropic effect, presumably through their ability to stimulate beta-1 receptors on the myocardium.60 Other beta-1 agonists (epinephrine, prenalterol, etc.) will also increase myocardial contractility, but most of these other beta-1 agonists will also increase heart rate or have other side effects that prevent their use in congestive heart failure. Dopamine and dobutamine are usually reserved for patients with advanced cases of congestive heart failure who do not respond to other positive inotropic drugs (e.g., digitalis).6,72... 

Peripheral dopaminergic receptor agents are useful in the treatment of congestive heart failure (Figure 35.7). Two distinct subtypes of dopamine receptors have been identified. The dopamine2 (DA2)... 

Dopamine stimulates dopamine, a-, and [3-adrenergic receptors. The use of dopamine in congestive heart failure is limited because it causes nausea and vomiting, becomes inactive when given orally, increases afterload (a-adrenergic receptor-mediated peripheral vasoconstriction), and enhances oxygen demand on the left ventricle. 

Correct answer = D. It is important to increase the cardiac output to improve oxygen delivery and thus minimize anaerobic metabolism and improve CNS and renal perfusion. Since this patient apparently does not have a heart condition, such as congestive heart failure, she could benefit from fluid therapy. An inotropic agent, such as dopamine, would lead to an increased cardiac output and dilation of the renal vasculature. [Note At high doses, however, it may constrict the renal beds due to interaction on a receptors.] Antibiotic administration is also important but will not improve the patient s hemodynamics. 

The discovery of the selective vasodilation produced by dopamine in the renal circulation and of its natriuretic effects, both mediated by D receptors, respectively in renal arteries and in renal tubules, prompted research of new D selective and peripherally acting agonists, potentially useful in the treatment of congestive heart failure and of hypertension. In the most severe forms of the former clinical condition, dopamine is used by intravenous infiision, taking... 

Peripheral dopaminergic receptor agents are useful in the treatment of congestive heart failure (CHF). Two distinct subtypes of dopamine receptors have been identified. The dopamine (DAi) receptors, which are located on vascular smooth muscles, cause vasodilation in the renal, mesentery, cerebral, and coronary vascular beds (see Figure 49). Thus, the pharmacologic response to activation of the DA2- and DAj-receptor receptors is hypotension, bradycardia, diuresis, and natriuresis. Fenoldopam is an orally active DA -receptor agonist. It is more potent than dopamine in causing... 

ADHD, attention-deficit/hyperactivity disorder AV, atrioventricular BPH, benign prostatic hypertrophy CAD, coronary artery disease CHF, congestive heart failure COPD, chronic obstructive pulmonary disease CV, cardiovascular DA, dopamine Dl, subtype 1 dopamine receptor Epi, epinephrine FFA, free fatty acids 5-HT, serotonin ISA, intrinsic sympathomimetic activity MI, myocardial infarction NE, norepinephrine NO, nitric oxide PVR, peripheral vascular resistance. 

Dopamine also stimulates cardiac Pi-receptors through both direct and indirect mechanisms. It is used to correct hemodynamic imbalances induced by conditions such as shock, myocardial infarction, trauma, or congestive heart failure. As a catechol and primary amine, dopamine is rapidly metabolized by COMT and MAO and, similar to dobutamine, has a short duration of action with no oral activity. It is administered as an intravenous infusion. 

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