Vasoconstrictive effects

Hypoperfusion of skeletal muscles leads to fatigue, weakness, and exercise intolerance. Decreased perfusion of the central nervous system (CNS) is related to confusion, hallucinations, insomnia, and lethargy. Peripheral vasoconstriction due to SNS activity causes pallor, cool extremities, and cyanosis of the digits. Tachycardia is also common in these patients and may reflect increased SNS activity. Patients will often exhibit polyuria and nocturia. Polyuria is a result of increased release of natriuretic peptides caused by volume overload. Nocturia occurs due to increased renal perfusion as a consequence of reduced SNS renal vasoconstrictive effects at night. In chronic severe HF, unintentional weight loss can occur which leads to a syndrome of cardiac cachexia. This results from several factors, including loss of appetite, malabsorption due to gastrointestinal edema, elevated metabolic rate, and elevated levels of proinflammatory cytokines. 

Vasopressin is a potent vasoconstrictor that increases blood pressure and systemic vascular resistance. It may have several advantages over epinephrine. First, the metabolic acidosis that frequently accompanies cardiopulmonary arrest can blunt the vasoconstrictive effect of epinephrine this does not occur with vasopressin. Second, stimulation of P receptors by epinephrine can increase myocardial oxygen demand and complicate the postresuscitative phase of CPR. Vasopressin can also have a beneficial effect on renal blood flow in the kidney, causing vasodilation and increased water reabsorption. 

Dopamine produces dose-dependent hemodynamic effects because of its relative affinity for cq-, /Jr, /J2-, and Dr (vascular dopaminergic) receptors. Positive inotropic effects mediated primarily by / -receptors become more prominent with doses of 2 to 5 mcg/kg/min. At doses between 5 to 10 mcg/kg/min, chronotropic and -mediated vasoconstricting effects become more prominent. Especially at higher doses, dopamine alters several parameters that increase myocardial oxygen demand and potentially decrease myocardial blood flow, worsening ischemia in some patients with coronary artery disease. 

Acute renal failure is a rare but serious side effect of ACE inhibitors preexisting kidney disease increases the risk. Bilateral renal artery stenosis or unilateral stenosis of a solitary functioning kidney renders patients dependent on the vasoconstrictive effect of angiotensin II on efferent arterioles, making these patients particularly susceptible to acute renal failure. 

Vasopressin causes vasoconstrictive effects that, unlike adrenergic receptor agonists, are preserved during hypoxia and severe acidosis. It also causes vasodilation in the pulmonary, coronary, and selected renal vascular beds that may reduce pulmonary artery pressure and preserve cardiac and renal function. However, based on available evidence, vasopressin is not recommended as a replacement for norepinephrine or dopamine in patients with septic shock but may be considered in patients who are refractory to catecholamine vasopressors despite adequate fluid resuscitation. If used, the dose should not exceed 0.01 to 0.04 units/min. 

Only a limited number of chemicals evoke a local quantifiable pharmacodynamic response, for example, the concentration-dependent vasoconstriction effect of corticosteroids. In these experiments, resulting skin blanching is scored visually by one or more qualified investigators, using an ordinal data scale. The lack of instrumentation has been criticized, because of possible subjective errors [25], However, approaches using the Chromameter device, although recommended by the FDA, have failed to return the desired precision [26, 27],... 

Topical corticosteroids produce anti-inflammatory, anti-itching, and vasoconstricting effects. A wide variety is available (described in detail in Drug Information 2004 and other references and compendia). Such steroids are classified into five categories that reflect a... 

Other mechanisms A few other effects of hypericin, and a crude hypericum extract have been found, including affinity for NMDA, inositol triphosphate, and adenosine receptors. However, these are not likely to be significant to its therapeutic effects because concentrations required for these interactions are not likely to be achieved by oral administration (Cott 1997). Vasoactive effects are possible because hypericum extracts blocked the vasoconstricting effects of histamine and prostaglandin F2o in porcine coronary arteries, and some vasorelaxation occurs in one particular fraction. These effects are hypothesized to be mediated by inhibition of phosphodiesterase (Melzer et al. 1991). 

In particular, postsynaptic Oi-blockers act on the o-receptive regions located on the smooth muscle of blood vessels and counteract the pressor, vasoconstricting effect of epinephrine and norepinephrine. In addition, they exhibit a direct relaxant effect on smooth muscle, which leads to peripheral dilation of blood vessels, which in turn raises blood pressure. However, they also exhibit a cardiostimulatory effect, which is frequently a cause of tachycardia. 

As an a-adrenoblocker, ergotamine exhibits a direct vasoconstricting effect for which it is used in medicine, particularly for alleviation of severe migraine attacks. It is categorically... 

Nephrotoxicity is the most common and the most serious long-term toxicity of amphotericin B administration. This drug reduces glomerular and renal tubular blood flow through a vasoconstrictive effect on afferent renal arterioles, which can lead to destruction of renal tubular cells and disruption of the tubular basement... 

Mechanism of Action A serotonin receptor agonist that binds selectively to vascular receptors, producing a vasoconstrictive effect on cranial blood vessels. Therapeutic Effect Produces relief of migraine headache. 

The duration of action of a local anaesthetic is proportional to the time that the drug remains bound to the sodium channels. Measures that prolong contact time will prolong the duration of the local anaesthetic effect. Cocaine has a vasoconstricting effect on blood vessels and prevents its own absorption. Many local anaesthetics are prepared with adrenaline (epinephrine) in order to achieve this effect. Concentrations are usually of the order of 1 200000 or more dilute than this. Care should be exercised when using adrenaline-containing solutions in the presence of halothane as it is known to sensitise the myocardium to the effects of catecholamines. 

Ropivacaine is an amide anaesthetic prepared as the pure S enantiomer of the racemic drug. Adverse cardiac effects appear to be stereo-selective for the R (-) enantiomer and so the intrinsic cardiotoxic potential of the drug may be reduced. Unlike other amide local anaesthetics it has a slight vasoconstricting effect. 

Erythroxylum coca Lam. Guo Yi (leaf) 1-cocaine, cinnamylococaine, alpha-trevilline, beta-trevilline, ecgonine, benzoylecgonine.33 For local anesthetic, has vasoconstriction effect. 

Neuropeptides Y (NFY) and YY are 36-residue amidated peptides that are members of the pancreatic polypeptide (PP) family (Fig. 30-5). NPY is produced both in the peripheral nervous system and in the brain,110 134 where it is one of the most abundant neuropeptides. Another member of the PP family is semi-nalplasmin, a regulator of calcium ion transport in bovine sperm.135 NPY is best known for its stimulation of appetite. It also inhibits anxiety and increases memory retention. It has a vasoconstrictive effect on blood vessels, participating in cardiovascular regulation.136 137 Peptide YY is formed in endocrine cells of the intestine, while NPY is formed in neurons of the parasympathetic system.138 Both participate in regulation of fluid and electrolyte secretion. Both are found in other vertebrate species.139... 

---