Drug effects feedback

The answer is d. (Murray, pp 258-297. Scriver, pp 2705-2716. Sack, pp 121-138. Wilson, pp 362-367.) Regulation of cholesterol metabolism is by definition exerted at the committed and rate-controlling step. This is the reaction catalyzed by 3-hydroxy-3-methylglutaryl CoA reductase. Reductase activity is reduced by fasting and by cholesterol feeding and thus provides effective feedback control of cholesterol metabolism. The statin class of drugs act at this site. 

Once calculated, the drug effect can be used to modify the parameters in the CV model, much hfee the neural and humoral reflexes. Resistances, comphances (including the unstressed volumes) of each segment, neural and humoral feedback gains, heart rate, and contractility are all typically modified by drugs. For example, sodium nitroprusside causes vasodilation and blood pooling therefore it would be made to primarily increase the compliance and unstressed volume of the veins, as well as to decrease arteriolar (peripheral) resistance [Greenway, 1982 Yu et ai, 1990]. 

Non-invasive monitoring of blood pressure has become increasingly important in research. High-Definition Oscillometry (HDO) delivers not only accurate, reproducible and thus reliable blood pressure but also visualises the pulse waves on screen. This allows for on-screen feedback in real time on data validity but even more on additional parameters like systemic vascular resistance (SVR), stroke volume (SV), stroke volume variances (SVV), rhythm and dysrhythmia. Since complex information on drug effects are delivered within a short period of time, almost stress-free and visible in real time, it makes HDO a valuable technology in safety pharmacology and toxicology within a variety of fields like but not limited to cardiovascular, renal or metabolic research. 

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