Peripheral blood vessels

P2 Peripheral blood vessels Bronchial smooth muscles... 

Vasoconstriction of peripheral blood vessels Regulates release of neurotransmitters decreases tone, motility, and secretions of gastrointestinal tract Increased heart rate, increased force of myocardial contraction... 

Phentolamine (Regitine) is used for its vasodilating effect on peripheral blood vessels and therefore may be beneficial in the treatment of hypertension caused by... 

Caffeine is a mild to potent CNS stimulant, with the degree of its stimulating effect dependent on the dose administered. Caffeine stimulates the CNS at all levels, including the cerebral cortex, die medulla, and the spinal cord. Caffeine has mild analeptic (respiratory stimulating) activity. Other actions include cardiac stimulation (which may produce tachycardia), dilatation of coronary and peripheral blood vessels, constriction of cerebral blood vessels, and skeletal muscle stimulation. Caffeine also has mild diuretic activity. 

Adrenoblocking drugs are classified as a-adrenoblockers, j8-adrenoblockers, and adrenergic neuron blockers depending on the response brought about in the organism. a-Adrenoreceptors cause dilation of peripheral blood vessels, and a few of them relax smooth muscles. 

Tolazoline is a weak, reversible a-adrenoblocker that lowers resistance of peripheral blood vessels and elevates venous capacity. However, it also exhibits 8-adrenomimetic activity, which consists of the stimulation of cardiac work and is manifest as tachycardia, chohn-ergic activity, which consists of stimulation of the gastrointestinal tract, and histamine-Uke activity, which consists of stimulation of gastric secretion. 

Mentha arvensis L. M. haplocalyx Briq. China Menthol, menthone, menthyl acetate.33 Stimulate gastrointestinal tract motility and central nervous system, dilate peripheral blood vessels. Increase sweat gland secretion. 

N.A. Veratrum viride Ait. Steroidal, alkaloids, chelidonic acid.99 Lower blood pressure, dilate the peripheral blood vessels. 

Progestogens, alone or together with estrogen, cause an increase in the width and tortuosity of peripheral blood vessels in the oral mucosa, which become more susceptible to local irritants and show increased permeability (204). 

The primary adverse effects associated with organic nitrates are headache, dizziness, and orthostatic hypotension.47 These effects are related to the drugs ability to dilate peripheral blood vessels and decrease peripheral resistance. Nausea may also be a problem in some patients. As indicated earlier, tolerance to the beneficial effects of nitrates can occur during continuous administration, but providing daily nitrate-free intervals should prevent this problem. 

Adverse effects of cocaine include constricted peripheral blood vessels, dilated pupils, and increased body temperature, heart rate, and blood pressure. Cocaine induces several immediate euphoric effects, such as hyperstimulation, reduced fatigue, and mental clarity, all of which depend on the administration route. The faster the absorption of cocaine, the more severe the effects. In contrast, faster absorption limits the duration of action. For example, the effect from snorting cocaine may last 15 to 30 minutes, whereas effects from smoking may last 5 to 10 minutes. Increased use can reduce the period of stimulation, as addicted humans may develop tolerance. In rare instances, sudden death may occur on the first use of cocaine or unexpectedly thereafter. 

Correct answer = D. Propranolol is a nonspecific p blocker that interferes with Pi receptors on the heart, causing bradycardia, that is, a slowing of the heart rate, Phenoxybenzamine blocks a receptors and prevents vasoconstriction of peripheral blood vessels by endogenous catecholamines. This leads to a decrease in blood pressure and peripheral resistance, which causes a reflex tachycardia. Isoproterenol is a potent p agonist that promotes tachycardia. Phentolamine is an a blocker that causes hypotension, which may set off refiex tachycardia. Prazosin is not indicated for tachycardia. 

Thrombin-Induced Rabbit Femoral Artery Thrombosis Localized thrombosis can also be produced in rabbit peripheral blood vessels such as the femoral artery by injection of thrombin, calcium chloride, and fresh blood via a side branch (Shebuski et al. 1988). 

These drugs act on postsynaptic acetylcholine receptors (cholinoceptors) at all the sites in the body where acetylcholine is the effective neurotransmitter. They initially stimulate and usually later block transmission. In addition, like acetylcholine, they act on the noninnervated receptors that relax vascular smooth muscle in peripheral blood vessels. 

Atropine has no significant effect on peripheral blood vessels in therapeutic doses but, in poisoning, there is marked vasodilatation. 

An interesting sidelight, Asians are often deficient in aldehyde dehydrogenase. About 50% of Japanese and Chinese people lack the mitochondrial enzyme. About 40 10 of native South Americans also lack the enzyme. This results in a number of adverse reactions to drinking alcohol, including facial flushing from dilation of peripheral blood vessels and increased heart rate. Apparently, these reactions are provoked by an unusual buildup of plasma acetaldehyde. 

Acebutolol is a beta-adrenoceptor antagonist with membrane-stabilizing activity that is sometimes cited as being cardioselective but has considerable effects on bronchioles and peripheral blood vessels. 

The postsjmaptic alpha-adrenoceptor antagonists, indor-amin, prazosin, and related quinazoline derivatives, block alphai-adrenoceptor-mediated vasoconstriction of peripheral blood vessels (both arterial and venous) and are effectively peripheral vasodilators (1,2). Qualitatively and quantitatively common adverse effects are generally similar, although indoramin has additional effects on other neurotransmitter systems and therefore tends to be considered separately. Their use in benign prostatic hyperplasia has been reviewed (3,4). 

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