Pressure changes, transients induced

In vivo, intravenous administration of ET-1 to conscious [20], anaesthetized [21] or pithed [22] rats produces a biphasic blood pressure response a small, transient depressor response followed by a prolonged pressor response. The systemic blood pressure changes induced by ET-1 are reflected in changes in regional haemodynamics, although the dilator response is not seen in all vascular beds [23-25], Big ET-1, when administered intravenously, is almost as potent as ET-1 in producing a pressor response which suggests effective in vivo conversion to ET-1 [22]. The haemodynamic effects of ET-1 have also been studied in man and pressor responses are seen after intravenous or intra-arterial administration [26-28]. 

In the 1950s, Hansell observed the production of drops by electro-mechanically induced pressure waves [8]. In this type of system, a voltage pulse applied to a piezoelectric material that is directly or indirectly coupled to the fluid, at ambient pressure, induces a volumetric change in the fluid. This volumetric change creates pressure/velocity transients within the fluid that are directed so as to produce a drop from an orifice [9-11]. Since the voltage is applied only when the drop is needed, these types of systems are called drop-on-demand or demand mode. ... 

The general experimental approach used in 2D correlation spectroscopy is based on the detection of dynamic variations of spectroscopic signals induced by an external perturbation (Figure 7.43). Various molecular-level excitations may be induced by electrical, thermal, magnetic, chemical, acoustic, or mechanical stimulations. The effect of perturbation-induced changes in the local molecular environment may be manifested by time-dependent fluctuations of various spectra representing the system. Such transient fluctuations of spectra are referred to as dynamic spectra of the system. Apart from time, other physical variables in a generalised 2D correlation analysis may be temperature, pressure, age, composition, or even concentration. 

Agents acting via oq-ARs to elicit changes in blood pressure induce a characteristic biphasic hemodynamic profile an initial, transient hypertensive response (by which peripherally located arterial oq-ARs constrict vascular smooth muscle) is followed by a longer-lived, centrally mediated attenuation of sympathetic outflow (culminating in a sustained drop in blood pressure). For this reason, oq-AR agonists are used to treat high blood pressure in some populations of hypertensive patients. 

As discussed above, agents acting via o -ARs to elicit changes in blood pressure induce a characteristic biphasic hemodynamic profile consisting of a transient hypertensive response followed by the sustained, centrally localized o -AR-mediated drop in blood pressure. As with the a2A-AR, mice null for the o ij-AR (a2B-AR / ) have documented the role of the a2B-AR subtype in modulating the pressor, or increased, blood pressure responses following a2-agonist activation of peripheral mechanisms (11). Control studies demonstrated that a2B-... 

Cardiovascular System Isoflurane produces a concentration-dependent decrease in arterial blood pressure cardiac output is maintained and hypotension is the result of decreased systemic vascular resistance. Vasodilation occurs in most vascular beds, particularly in skin and muscle. Isoflurane is a potent coronary vasodilator, simultaneously producing increased coronary blood flow and decreased myocardial consumption. Patients anesthetized with isoflurane generally have mildly elevated heart rates as a compensatory response to reduced blood pressure however, rapid changes in isoflurane concentration can produce both transient tachycardia and hypertension due to isoflurane-induced sympathetic stimulation. 

If a transient temperature field exists in the saturated rock, the difference in coefficient of thermal expansion of the pore fluid and the rock matrix can induce changes in pore pressure and stresses. This can lead to thermal-induced pore fluid flow and deformation of the rock around the borehole. 

There are clear reports of clinical concern. Grossman and Messerli (Grossman and Messerli 2012), for example, observed that severe hypertension involving encephalopathy, stroke, and irreversible renal failure have been reported. However, there is still a lack of systematic study of this area, and the clinical relevance of small, transient drug-induced changes in blood pressure to symptomatology, morbidity, or mortality is not well characterized (O Brien and Turner 2013). 

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