Biotransformation and urinary excretion of 4-substituted amphetamines in pregnant mice.

The urinary elimination of 4-hydroxyamphetamine (PHA) and a series of homologous 4-alkoxy-substituted amphetamines and their metabolites was examined after single and multiple oral administration to pregnant and non-pregnant mice. The metabolic profile and extent of biotransformation in a series of alkoxy analogues were affected by the size of the alkoxy side chain, multiple dosing and pregnancy. There were increased recoveries of both the substrate and the conjugated derivative of PHA during gestation. The major metabolic routes observed were O-dealkylation, conjugation, and aliphatic hydroxylation of the propoxy side chain. There was some evidence of oxidative deamination. Pregnancy did not alter the profile of the major metabolites detected by GLC and NMR spectroscopy.

Diphenylamine-2-carboxylate analogues block Cl- conductances in A7r5 cells by affecting cellular Ca2+ homeostasis.

We have investigated the cellular signalling pathway by which vasopressin stimulates a Ca2(+)-dependent Cl- conductance and the effects of two known Cl- channel blockers in cultured rat A7r5 aortic smooth muscle cells using anion efflux and fluorescent Ca2+ imaging studies. Addition of vasopressin (100 nM) to A7r5 cells enhanced 125I (Cl- substitute) efflux from the cells through a V1 receptor-mediated pathway. Maximal increases in the rate of efflux were observed 1 min following addition of vasopressin (4-fold above basal levels). Activation of the V1 pathway was demonstrated by an increase in inositol trisphosphate (IP3) formation and lack of cAMP accumulation by the cells following the addition of vasopressin. Fluorescent ratio imaging with fura-2 revealed that addition of vasopressin to the cells results in an increase of [Ca2+]i which peaks within 20 s and does not return to resting levels during the 100 s observation period. The addition of a Ca2+ ionophore mimicked the vasopressin-induced efflux from the cells. 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and a chloro-substituted compound (cpd 149) inhibited the vasopressin-stimulated 125I efflux from the cells. The concentrations of NPPB and cpd 149 required to inhibit 125I efflux from the cells were similar to those which also attenuated vasopressin-induced Ca2+ transients in the cells. NPPB and cpd 149 had no effects on the ionomycin stimulated efflux. The mechanism(s) by which cpd 149 exerts its effect on stimulated efflux was examined by measuring its action on vasopressin-induced changes in IP3. Compound 149 inhibited IP3 generation in response to vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro assessment of cytotoxicity and biotransformation of propranolol in Cunninghamella echinulata.

1. Biotransformation studies with five concentrations of racemic propranolol were conducted using the filamentous fungus Cunninghamella echinulata ATCC 9244. 2. The rate of formation and subsequent disappearance of a new major metabolite, 8-hydroxypropranolol, was dose-dependent. Desisopropylpropranolol and 4-hydroxypropranolol were also formed. 4-Hydroxypropranolol was the major fungal metabolite in earlier studies. 3. Propranolol exerted a dose-dependent response on biotransformation, fungal growth, dextrose utilization, ammonia formation and incubation broth pH. Determination of dextrose utilization and incubation broth pH would provide reliable, cost-effective and convenient alternative methods for cytotoxicological evaluation.

Biotransformation of 2-, 3-, and 4-methoxy-amphetamines by Cunninghamella echinulata.

1. Three methoxyamphetamine analogues have been incubated with Cunninghamella echinulata under different environmental and nutrient conditions. 2. The biotransformation of 4-methoxyamphetamine was inhibited by cobalt; the carbon source and other trace metals had no effect. The rate of biotransformation of 4-methoxyamphetamine and formation of 4-hydroxyamphetamine was greater in cultures incubated on 30 degrees angle brackets rather than flat. 3. Carbon monoxide, ethanol and quinidine had a significant effect on methoxyamphetamine metabolism. 4. Metabolism was influenced by the position of the methoxy side-chain and substrate concentration. In day 7 samples the relative order for biotransformation was 3- greater than 4- greater than 2-methoxyamphetamine. 5. O-Demethylation was the major metabolic route in the biotransformation of 4-methoxyamphetamine but occurred to a lesser extent with 3-methoxyamphetamine, and was only a trace pathway with 2-methoxyamphetamine. N-acetylation was a trace pathway.

The biotransformation of tranylcypromine by Cunninghamella echinulata.

When incubated alone for 7 days with the fungus Cunninghamella echinulata, tranylcypromine was extensively metabolized. As observed in mammalian systems, N-acetyltranylcypromine was the major metabolite recovered along with lesser amounts of 4-hydroxytranylcypromine, as its N,O-diacetyl derivative. The rate and extent of tranylcypromine biotransformation was affected by whether incubation was on either 30 degrees or flat brackets with a gyratory shaker. There is a strong association between the rate of biotransformation and the utilization of glucose, formation of ammonia, and pH. The slowest rates of biotransformation and metabolic response were observed with the large fungal pellets formed during incubation on flat brackets. These findings raise the possibility that, as in mammalian systems, fungal metabolism of xenobiotics can be affected by nutrient and environmental conditions.