Metabolism-blood flow coupling

Barbiturates depress neuronal activity in the CNS. This is accompanied by decreased cerebral metabolic oxygen consumption and decreased cerebral blood flow, since the coupling of blood flow to brain metabolism is preserved with the barbiturates. It also results in a decrease in ICP. Barbiturates depress neuronal activity in the cerebral cortex, thalamus and motor centers. Barbiturates are effective anticonvulsants (see Ch. 9), reduce intraocular pressure, increase the threshold of spinal reflexes and provide excellent muscle relaxation. The barbiturates lack specific analgesic effects and are, therefore, not suitable as the sole anesthetic for invasive procedures. 

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Whitesell RR, Ward M, McCall AL, Granner DK, May JM (1995) Coupled glucose transport and metabolism in cultured neuronal cells determination of the rate-limiting step. J Cereb Blood Flow Metah 75 814-826,... 

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Pickard, J. D., 1981 Role of prostaglandins and arachidonic acid derivations in the coupling of cerebral blood flow to cerebral metabolism. J. Cereb. Blood Flow Metab. 1, 361-384. 

Sakabe, T., Siesjo, B. K., 1979 The effect of indomethacin on the blood flow-metabolism couple in the brain under normal hypercapnic and hypoxic conditions. Acta Physiol. Scand. 107, 283-284. 

Paradoxically, the structures and functions of the liver predispose it to chemical toxicity. Hepatocytes are exposed to orally administered xenobiotics without systemic modification or dilution because they flow directly to the liver by the portal venous blood that delivers absorbed nutrients from the gastrointestinal tract. Xenobiotics may be extensively metabolized by the liver so that little of the parent xenobiotic enters the systemic circulation, a phenomenon known as the first pass effect. The movement of xenobiotics into the liver coupled with an opposing move-... 

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