Vasoconstriction animal models

A variety of vasoactive substances may modulate the CM-induced vasoconstriction, including prostaglandins, ANF, adenosine, endothelin, vasopressin, noradrenahne and angiotensin [53A, 55]. Of particular interest has been the possible role of superoxide radicals in the pathogenesis of CMIN. Not only do they induce renal vasoconstriction, but, as noted above, they also cause direct renal cell injury. Superoxide dismutase prevents the fall in GFR associated with CM, while in a dehydrated animal model, renal levels of superoxide dismutase is diminished which may account for the demonstrated increased susceptibility to... 

Now, suppose the lABG team has successfully shown that the system can be manufactured and it works both in bench studies and in animal models. The sensor set is deemed ready to be taken to the relatively unknown territory of the radial artery of a sick patient. The radial artery has been used for pressure measurement but only an intact blood column to the central arteries is needed for pressure measurement and there is not necessarily substantial blood flow. Blood sampling is often performed as a passive activity that allows a syringe to fill by the action of the pressure. lABGs require reasonable flow to bring sample to the sensors. Cold, peripheral vasoconstriction, hypotension, and mechanical... 

Cardiovascular The safety of oxytocin during cesarean section has been reviewed [55 , 56"]. Oxytocin causes peripheral vasodilatation and hypotension, leading to increases in heart rate, cardiac output, and pulmonary arterial pressure. However, animal models suggest that oxytocin differentially affects the coronary vasculature and causes vasoconstriction. Oxytocin boluses of 10 lU have been associated with maternal deaths in patients with underlying cardiac disease or pre-existing hypotension. The prevalence of hypotension after an oxytocin bolus depends on the dose and speed of... 

In the early 1940s, the effect of induced ischemic myopafhy on renal perfusion in the rabbit was studied. It was conclusively demonstrated in this model that there was extreme renal cortical vasoconstriction with preservation of the medullary circulation [17]. This early first demonstration of posttrauma tic vasomotor nephropathy was independently confirmed 20 years later in the USA when preferential renal cortical ischemia was demonstrated in acute kidney injury in man. Since then, many animals have been used to study pathogenesis of AKL Rats and mice are the most popular experimental animals now. Dogs and rabbits are now less often used. Rats and mice are becoming more and more acceptable animals because they are easy to breed. Pigs are also being used [18,19]. 

As mentioned earlier, survival of ischemic penumbra is highly dependent on the efficiency of collateral vasculature to provide adequate CBF in the periphery of the ischemic territory. The viability of the penumbra depends on the degree and the duration of ischemia. In animal stroke models the reduction of CBF in the periphery of the ischemic territory is down to about 20% (Jones et al., 1981). Similar levels of diminished CBF are observed in humans (Bandera et al., 2006). In a healthy brain, CBF is maintained between 60 and 150 mmHg by vasoconstriction or vasodilatation in response to changes of perfusion pressure. However, during ischemia this autoregulation is lost, which makes the penumbra highly dependent on systemic blood pressures. 

Documented effects In experiments with animals, the alkaloid thalisopine acted as a sedative and had pronounced anticonvulsant activity which surpassed that of phenytoin and trimetin (Tashbaev and Sultanov 1962, 1965). When injected intravenously, it had distinct antiarrhythmic action on experimental models (Akbarov et al. 1972). The alkaloid cryptopine stimulated uterine smooth muscles, had vasoconstrictive action, and increased arterial pressure in narcotized animals. The alkaloid magnoflorine reduced blood pressure due to its ganglio-blocking action (Fakhratdinov 1971 Fakhrutdinov and Sultanov 1972). In anesthetized animals, intravenous injections of the alkaloid thaUcminine caused short-term reduction of blood pressure and heart rate (Abdalla et al. 1991). 

Cerebral insufficiency refers to describe the people with age-related decline in mental function and decrease blood flow to the brain cause by clogged arteries. Platelet activating factor (PAF) is an inflammatory mediator, plays an important role in allergy, inflammatory processes, coronary, and cerebral vasoconstriction [178]. The production and release of PAF in the brain under various pathological conditions, including oxidant stress-induced ischemic injury [179]. The efficiency of EGb-761 on cerebral circulation and metabolism has been demonstrated in various models of cerebrovascular insufficiency and showed beneficial effect like cerebral edema in rats intoxicated with triethyltin chloride (TET) [180]. Moreover, oral or intravenous administrations EGb decrease cerebral edema development in gerbils [181]. In an animal study [182], EGb-761 and an extract of local ginkgo... 

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