Tolerance of neuromuscular blocking agents

3 times for 15 sec. Activity of 8-aminolevufinate synthase (ALA-S) is measured following the radiochemical method of Strand et al. (1972) with [14C]succinic acid and a succinyl-CoA-generating system. Enzyme activity is expressed as pmoles 8-aminolevufinic acid per 30 min per mg of protein. Ferrochelatase activity is measured using a modified radiochemical method (Bonkowsky et al. 1975 Deybach et al. 1981). 

To measure cytochrome P-450, 10 ml of the 800 g supernatant are centrifuged at 12 000 g for 15 min 5 ml of the supernatant are then centrifuged at 105 000 g for 30 min, after washing twice, microsomes (pellet) are resuspended in phosphate buffer and the protein concentration adjusted to 2 mg/ml. The level of cytochrome P-450 is measured in the microsomal fraction using the method of Omura Sato (1964). 

The tests allow judgement of the propensity of local anesthetics to induce symptoms of hepatic porphyria. The local anesthetics lidocaine, bupivacaine, etido-caine, mepivacaine, prilocaine and pyrocaine belong to this group, but procaine, butacaine, oxybuprocaine, proxymethacaine and tetracaine had no (or very slight) porphyrinogenic effect. 

Bayar Sumer (1995) investigated the effect of some local anesthetics on methemoglobin levels and erythrocyte enzymes. 

Anderson KE (1978) Effects of antihypertensive drugs on hepatic heme biosynthesis, and evaluation of ferrochelatase inhibitors to simplify testing of drugs for heme pathway induction. Biochem Biophys Acta 543 313-327 Bayar C, Sumer N (1995) The effect of some local anesthetics on methemoglobin levels and erythrocyte enzymes. Turk J Med Sci 26 439-443 

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