DL-isoproterenol and

In this chapter some recent data on the effects of ischemia produced by the sympathomimetic agents, DL-isoproterenol and me-thoxamine, on taurine levels in rat heart, blood and liver will be discussed. Also previously published experiments from our laboratory concerning the ischemic effects of ligation of a coronary vessel in the dog (Crass and Lombardini, 1977) and anoxic perfusion of isolated rat hearts (Crass and Lombardini, 1978) on cardiac taurine levels will be reviewed. 

The effects of ischemia on taurine levels were measured in three types of animal models ligation of the circumflex artery in the dog perfusion of rat hearts with oxygen-deficient buffer and administration of toxic doses of DL-isoproterenol and methoxamine. 

Harrison, W. H., Gray, R. M., and Solomon, L. M., Incorporation of L-DOPA, L-a-methylDOPA and DL-isoproterenol into guinea pig hair, Acta Dermatovener (Stockholm), 54, 249,1974. 

Papavasiliou and colleagues demonstrated an intracellular increase in the concentration of manganese in liver tissue after the administrations of DA, L-epinephrine, or DL-isoproterenol. It was also observed that this effect was mediated through an intracellular increase in cyclic 3, 5 -adenosine monophosphate. Although the importance of these studies in relation to manganese encephalopathy could not be evaluated, it became clear that a correlation existed between manganese metabolism and biogenic amines. 

Taurine content of control rat ventricles was shown to be 97.6 2.9 ymoles g dry wt (Fig. 2). Administration of cardlo-toxic doses (80 mg/kg) of DL-isoproterenol (ISO) decreased the taurine content in rat ventricles by 29.6% (68.7 2.6 ymoles) after 7 hours and by 42.0% (56.6 8.4 ymoles) after 24 hours. The concentration of taurine in the blood Increased from 0.226 0.016 to 0.442 0.033 ymoles ml seven hours after ISO administration and returned to control values (0.256 0.023 ymoles) after 24 hours. Liver taurine content did not change 7 hours after administration of ISO although after 24 hours taurine levels decreased but not significantly (p > 0.05). 

Effect of DL-isoproterenol on taurine levels in rat ven-triolesy liver and blood. Animals were killed seven or 24 hours after administration of 80 mg/kg of DL-isopro-terenol or saline. Eumber of animals per group is shown in parentheses. (Mean S.E.)... 

The total amino acid pattern of blood was also analyzed (Table 2). The concentrations of most of the essential amino acids (threonine, valine, isoleucine, leucine, and arginine) decreased significantly after administration of DL-isoproterenol. In addition, the concentrations of serine, alanine, tyrosine and ornithine were reduced. Changes in amino acid concentrations varied from 33% to 63%. 

In all experiments taurine levels decreased in cardiac tissue. In the model which utilized S3nnpathomimetic agents an increase in blood taurine levels was observed. The total amino acid pattern was measured in ventricular and blood tissues after DL-isoproterenol ad-ministration In ventricular tissue the levels of most of the amino acids remained constant thus attesting to the specificity of taurine loss. On the other hand, in blood most of the essential amino acids decreased seven hours after DL-isoproterenol administration and returned to control values after 24 hours. 

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