Reference

Comparison of dose/conductance curves for GABA and some structurally related compounds at the lobster inhibitory neuromuscular junction

Comparison of dose/conductance curves for GABA and some structurally related compounds at the lobster inhibitory neuromuscular junction. Constanti, A. (Dep. Pharmacol., St. Bartholomew's Hosp., London, Engl.). Neuropharmacology, 16(5), 367-74 (English) 1977. CODEN: NEPHBW. DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) .gamma.-Amino-.beta.-hydroxybutyric acid (I) [352-21-6] (50.mu.M-3.2mM) and .delta.-aminovaleric acid (II) [660-88-8] (200.mu.M-10mM) log-dose/conductance curves at the lobster, Homarus vulgaris, inhibitory neuromuscular junction, paralleled those of GABA [56-12-2], and could be explained by the 2 independent binding site receptor model, (dissocn. const., K, 275 and 945.mu.M for I and II resp.). Guanidoacetic acid (III) [352-97-6] curves were not parallel to, and had different max. to, the GABA curves, and was fitted by a modified 2 binding site model with K1 7.4.mu.M and K2 92.mu.M. GABA, I, and II may be agonists of comparable intrinsic activity, but differing receptor affinities, whereas III may be only a partial agonist.

Ruminal digestion of chloroplasts and the protection of protein by glutaraldehyde treatment

Ruminal digestion of chloroplasts and the protection of protein by glutaraldehyde treatment. Mangan, J. L.; West, Janet (Biochem. Dep., ARC Inst. Anim. Physiol., Babraham/Cambridge, Engl.). J. Agric. Sci., 89, Pt. 1, 3-15 (English) 1977. CODEN: JASIAB. DOCUMENT TYPE: Journal CA Section: 18 (Animal Nutrition) Chloroplasts, 50-80% intact, were prepd. from kale (Brassica oleracea var. Marrowstem) by rapid homogenization (3.5 s) of deveined leaves into partially frozen buffer pH 7.4 made 0.4 M with sucrose, and sepd. by differential centrifugation. Chloroplasts from 10 kg leaves were administered to the rumen of a sheep and the degrdn. followed by anal. of the rumen fluid which was collected continuously. Particulate matter of the rumen fluid was sepd. on discontinuous sucrose d. gradients, 8 ml each of 35, 46, 50, 65, and 75% (wt./vol.), centrifuging at 300 g for 1 h at 2.degree.. Chloroplasts were rapidly ingested by entodiniomorphid protozoa and digested with no detectable increase in sol. N in the rumen fluid. No net prodn. of NH3 occurred but .delta.-aminovaleric acid [660-88-8] increased, indicating that amino acid transformations had occurred. Chlorophyll in the ingested chloroplasts was rapidly degraded with a half-life of 50-60 min. In contrast a similar amt. of soluble casein added to the rumen degraded with a half-life of 13-14 min with large increase in sol. N consisting of peptides, amino acids, NH3 and .delta.-aminovaleric acid. Glutaraldehyde [111-30-8]-treated chloroplasts were also ingested by protozoa; chlorophyll was rapidly degraded but there was no increase in the sol. N of the rumen fluid, including NH3 and .delta.-aminovaleric acid. Water-disrupted chloroplasts released sol. protein and in the rumen behaved like casein, producing high proportions of NH3 and .delta.-aminovaleric acid. The significance of these experiments in the protection of sol. leaf protein from degradation in the rumen of pasture-fed animals is discussed.