Blood-flow-stimulating activity

Stevia Stevia rebaudiana) Uses Natural sweetener, hypoglycemic and hypotensive properties Actions Multiple chemical components sweetness d/t glycoside, stevioside hypotensive effect may be d/t diuretic action or vasodilation action Available forms Liq extract, powder, caps Notes/SE HA, dizziness, bloating Interactions T Hypotensive effects W/ antihypertensives esp CCB, diuretics EMS Monitor BP does not encourage dental caries may -1-glucose St. John s Wort (Hypericum perforatum) Uses Mild-mod depression, anxiety, anti-inflammatory, immune stimulant/anti-HIV/antiviral, gastritis, insomnia, vitiligo Action MAOI in vitro, not in vivo bacteriostatic bactericidal, T capillary blood flow, uterotonic activity in animals Efficacy Variable benefit w/ mild-mod depression in several trials, but not always seen in clinical practice Available forms Teas, tabs, caps, tine, oil ext for topical use Dose 2-4 g of herb or 0.2-1 mg of total hypericin (standardized extract) daily Notes/SE Photosensitivity (use sunscreen) rash, dizziness, dry mouth, GI distress Interactions Enhance MAOI activity, EtOH, narcotics, sympathomimetics EMS T Risk of photosensitivity Rxns t effects of opioids and sympathomimetics... 

BP is also regulated by hormonal feedback (humoral). Hypotension decreases renal blood flow and activates the release of renin, which leads to the formation of angiotensin II, which in turn stimulates the release of aldosterone from the adrenal cortex. Aldosterone promotes water and salt retention, increasing blood volume and as a consequence increases SV and CO. 

Neuromedin U is a neuropeptide which is widely distributed in the gut and central nervous system. Peripheral activities of neuromedin U include stimulation of smooth muscle, increase in blood pressure, alteration of ion transport in the gut, control of local blood flow and regulation of adrenocortical function. The actions of neuromedin U are mediated by G-protein coupled receptors (NMU1, NMU2) which are coupled tO Gq/11. 

As to be expected from a peptide that has been highly conserved during evolution, NPY has many effects, e.g. in the central and peripheral nervous system, in the cardiovascular, metabolic and reproductive system. Central effects include a potent stimulation of food intake and appetite control [2], anxiolytic effects, anti-seizure activity and various forms of neuroendocrine modulation. In the central and peripheral nervous system NPY receptors (mostly Y2 subtype) mediate prejunctional inhibition of neurotransmitter release. In the periphery NPY is a potent direct vasoconstrictor, and it potentiates vasoconstriction by other agents (mostly via Yi receptors) despite reductions of renal blood flow, NPY enhances diuresis and natriuresis. NPY can inhibit pancreatic insulin release and inhibit lipolysis in adipocytes. It also can regulate gut motility and gastrointestinal and renal epithelial secretion. 

Activation of both the RAAS and the SNS also contribute to vasoconstriction in an attempt to redistribute blood flow from peripheral organs such as the kidneys to coronary and cerebral circulation.7 However, arterial vasoconstriction leads to impaired forward ejection of blood from the heart due to an increase in afterload. This results in a decrease in CO and continued stimulation of compensatory responses, creating a vicious cycle of neurohormonal activation. 

During phase I, each seizure causes a sharp increase in autonomic activity with increases in epinephrine, norepinephrine, and steroid plasma concentrations, resulting in hypertension, tachycardia, hyperglycemia, hyperthermia, sweating, and salivation. Cerebral blood flow is also increased to preserve the oxygen supply to the brain during this period of high metabolic demand. Increases in sympathetic and parasympathetic stimulation with muscle hypoxia can lead to ventricular arrhythmias, severe acidosis, and rhabdomyolysis. These, in turn, could lead to hypotension, shock, hyperkalemia, and acute tubular necrosis. 

Sympathetic and parasympathetic nerves innervate the penis. In the flaccid state, OC2-adrenergic receptors mediate tonic contraction of the arterial and corporal smooth muscles. This maintains high penile arterial resistance and a balance exists between blood flow into and out of the corpora. With sexual stimulation, nerve impulses from the brain travel down the spinal cord to the thoracolumbar ganglia.3 A decrease in sympathetic tone and an increase in parasympathetic activity then occurs, causing a net increase in blood flow into the erectile tissue. Erections may also occur as a result of a sacral nerve reflex arc while patients are sleeping (nocturnal erections). 

Loss of plasma volume leads to a decrease in MAP. Baroreceptors located in the aortic and carotid sinuses detect this fall in MAP and elicit reflex responses that include an increase in the overall activity of the sympathetic nervous system. Sympathetic stimulation of the heart and blood vessels leads to an increase in cardiac output (CO) and increased total peripheral resistance (TPR). These adjustments, which increase MAP, are responsible for the short-term regulation of blood pressure. Although increases in CO and TPR are effective in temporary maintenance of MAP and blood flow to the vital organs, these activities cannot persist indefinitely. Ultimately, plasma volume must be returned to normal (see Table 19.1). 

Increases in cerebral blood flow elicited from stimulation of the basal forebrain are mediated by nicotinic and not muscarinic receptors (Linville et al. 1993). During an attention task, nicotine increases cerebral blood flow to the the anterior cingulate cortex, cerebellum, and occipital cortex, supporting its role in activating attentional systems (Ghatan et al. 1998). 

In addition to autonomic effects, areca produces mental stimulation, increases cerebral blood flow and glucose metabolism, and creates electrophysiological activation as seen on the EEG. 

Some functional neuroimaging studies have examined the effects of scopolamine in cognitive tasks. Although scopolamine inhibits increases in cerebral blood flow to somatosensory stimulation, it does not inhibit the neural response (Ogawa et al. 1994). Thus, cholinergic systems may be involved in coordination of cerebral blood flow increases to neural activation. Subjects performing an attentional auditory discrimination... 

Physical activity increases blood flow through the muscle by stimulation of cardiac output, by increasing the diameter of arterioles (vasodilatation) that supply the muscle and by decreasing the flow through abdominal and pelvic viscera and the Uver (vasoconstriction) so that more is... 

Figure 19.17 The biochemistiy and physiology responsible for penile erection. Sexual activity itself begins with a state of arousal that leads to erection. Arousal results in part from stimulation of the sense organs. The hypothalamus coordinates the sensations and activates the autonomic nervous system. Sensory nerves from the skin of the penis and other erogenous zones stimulate the parasympathetic system. This activates nitric oxide synthase and the resultant nitric oxide, via cyclic GMP, causes vasodilation of the arterioles. This increases blood flow through the corpora cavernosa which then expands producing an erection. Pheromones secreted by the female can stimulate the odour detecting system in the nasal cavity of the male (Chapter 12 and see above). Stress, however, activates the sympathetic system releases cyclic AMP which can result in vasoconstriction of the arterioles. Other factors that can interfere with an erection are physical fatigue and alcohol.

The activity of this enzyme is regulated by changes in the concentrations of ATP and phosphate the former inhibits whereas the latter activates it. These are the signals that increase the concentration of adenosine. It is transported out of the cell, so that the extracellular concentration also increases. This then stimulates relaxation of the smooth muscle in the arterioles which results in vasodilation and increased blood flow and consequently a greater supply of oxygen to the cardiomyocytes. The blood flow will be increased to those parts of the myocardium that are not totally occluded by the clot, so that more mitochondrial generation of ATP can occur. Provided the portion of the myocardium that is totally occluded is not too large, the heart can then continue to function as a pump. 

CNS stimulants can be classified as Psychomotor stimulants compounds that display a stimulatory effect primarily on brain functions and which activate mental and physical activity of the organism. They are made up of methylxanthines (caffeine, theophylline, pentoxifyllin), amphetamines (dextroamphetamine, methamphetamine), and also methylphenidate and pemoline. Respiratory stimulants or analeptics compounds, which cause certain activations of mental and physical activity of the organism, and primarily excite the vasomotor and respiratory centers of the medulla (doxapram, almitrine).Drwgi that suppress appetite or anorectics drags that activate mental and physical activity of the organism, but primarily accentuate the excitatory center of satiation in the hypothalamus (phentermine, diethylpropion).In order to increase mental capability, nootropics — drugs that increase the functional state of the brain — are sometimes used, the effect of which is associated with blood flow and metabolism of the brain. 

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