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Background: Accumulating evidence indicates that adenosine monophosphate (cAMP)‐dependent protein kinase A (PKA) is involved in the neurobiological responses to ethanol. Previous reports indicate that mice lacking the RIIβsubunit of PKA (RIIβ−/−) voluntarily consume more ethanol than wild‐type controls (RIIβ+/+) using 2‐bottle testing procedures. Although such procedures primarily measure consummatory behavior, operant self‐administration procedures allow analysis of consummatory as well as appetitive or “ethanol‐seeking” behavior (i.e., lever pressing is required to gain access to the ethanol solution). Therefore, we determined whether the high ethanol consumption characteristic of RIIβ−/−mice would be complemented by increased appetitive ethanol‐seeking behavior in an operant paradigm.

Supernatant fluid obtained from homogenates of chicken uropygial gland was incubated with androst-4-ene-3,17-dione-4-14C in the presence of penicillin and streptomycin. Two metabolic products were isolated and identified by using preliminary thin-layer chromatography followed by gas chromatography of the free metabolites, trimethylsilyl ethers, o-methyloxime derivatives, and double derivatives on 1 percent SE-30 and 1 percent neopentyl glycol succinate (NGS) columns. Crystallization to constant specific activity was also used for the identification of the metabolites. The metabolites identified were 3α-hydroxy-5α-androstane-17-one and 5α-androstane-3α,17β-diol. The isolated organisms from the supernatant fluid were highly susceptible to the activity of the antibiotics added to the incubation mixture for metabolic activity. The minimal concentrations of the antibiotics required to inhibit bacterial growth under the experimental conditions of this investigation were determined.

Study of the antimicrobial spectrum of valinomycin revealed that, in addition to the gram-positive bacteria reported in literature, Streptococcus pyogenesand Clostridium sporogenesare also susceptible to this antibiotic. The minimal inhibitory concentrations (MIC) of the antibiotic for S. pyogenesgrown aerobically and anaerobically did not differ markedly, negating the hypothesis that oxidative phosphorylation is involved in the mechanism of action of this antibiotic. This conclusion is further strengthened by the inhibition of growth of C. sporogenes, an obligate anaerobe. In a medium with a low K+concentration, the MIC for S. pyogeneswas 0.02 µg/ml, the lowest ever recorded for this antibiotic. The inhibition of growth of S. pyogenesand C. sporogeneswas readily reversed by addition of K+to the medium, indicating a compensation for net efflux of K+from the cells when the transmembrane potential reached equilibrium. In contrast to these bacteria, Bacillus subtiliswas less susceptible to the antibiotic when the potassium concentration of the medium was low. The addition of potassium in the presence of valinomycin increased the inhibition of growth, which appears to result from dissipation of metabolic energy as in the mitochondrial system.