Comparative biochemistry and physiology. C: Comparative pharmacology最新文献

1. Digestive enzyme activity and the oxygen consumption rate of Acartia clausi from the polluted eutrophic Elefsis Bay and the non-polluted oligotrophic Vouliagmeni-Fleves area were compared.

2. Out of 13 hydrolases whose activity was revealed, 10 had a higher activity in the Elefsis population than in the Vouliagmeni-Fleves one. Only amylase, alkaline phosphatase and esterase lipase had a higher activity in the Vouliagmeni-Fleves population.

3. The high activity of amylase in Vouliagmeni-Fleves population seems to indicate that phytoplankton constitutes the most important part of A. clausi's food.

4. Respiration rate was significantly lower in Elefsis population, irrespective of season.

5. A significant seasonal variation was observed which was greater in the Vouliagmeni-Fleves population, with a 50% decrease in the respiration rate between spring and summer.

6. The obtained results agree with previous literature data and show the physiological characteristics of A. clausi of Elefsis Bay, allowing it to thrive in polluted eutrophic waters.

1. The effect of cadmium, lead, and mercury on 5-aminolevulinic acid (ALA), porphobilinogen (PBG), and PBG synthase was determined in hepatopancreas of the bivalve, Cerastoderma edule (L.).

2. Cd and Hg exposure induced increased ALA content, and thus an initial doubling of ALA within 24 hr.

3. Using ALA in excess (8 mmoll⁻¹) as substrate, no PBG synthase (ALA dehydratase, EC 4.2.1.24) activity was detectable in freshly prepared hepatopancreas homogenates.

4. Increased ALA in metal exposed bivalves is not a simple effect due to metal inhibition of PBG synthase.

5. The observed lack of PBG synthase suggests an alternative to the general pathway where two ALA molecules condense to one PBG.

1. The quality of unfertilized eggs of the sea urchin Strongylocentrotus intermedius, kept for a long time (50 days) in a sea water containing water soluble hydrocarbons of diesel fuel in sublethal concentrations (0.3–0.04 mg/l), was assessed through observation of embryogenesis and the intensity of ⁴⁵Ca²⁺ uptake.

2. It has been shown that such treatment led to delay and asynchronism of embryonal and larval development and to appearance of a greater number of abnormalities compared to the control.

3. Unfertilized eggs of sea urchins exposed to the hydrocarbons in sublethal concentrations accumu- lated 30–60% more ⁴⁵Ca²⁺ than those of control animals. Short-term incubation (2 hr) of eggs at the same hydrocarbon concentrations did not change ⁴⁵Ca²⁺ uptake by unfertilized eggs of control animals.

4. The increase of hydrocarbon concentration up to 1 mg/l (i.e. to a concentration causing disturbance of embryogenesis in acute experiments) in short-term experiments caused a small elevation in the ⁴⁵Ca²⁺ uptake by unfertilized eggs of control animals (30% more than in untreated eggs).

5. Ionomycin-induced (concentration 10⁻⁸−10⁻⁹) increase of ⁴⁵Ca²⁺ uptake by unfertilized eggs (50–100% more than the untreated eggs) caused the same disturbance of embryogenesis as under hydrocarbon exposure.

6. It is suggested that one of the mechanisms inducing the deleterious effect of hydrocarbons in sea urchin gametes is related to the increase of membrane permeability to calcium ions.

1. Adaptation of muscarinic receptors (MR)—muscarinic stimulation—induced intracellular Ca²⁺ mobilization during short-heat exposure (33°C).

2. Heat-exposure for 48 hr decreased the carbachol (CCh)-stimulated cytosolic C²⁺ concentration increase.

3. The number of MR on cell surface increased transiently at 24 hr with a subsequent decrease at 48 hr.

4. CCh-stimulated inositol trisphosphate (IP₃) formation decreased at 48 hr.

5. In saponin-permeabilized cells, 1,4,5-IP₃-induced ⁴⁵Ca²⁺ release decreased at 24 hr.

6. The data suggest that the adaptation for increased muscarinic stimulation occurs at IP₃ generating sites as well as at intracellular IP₃ receptor sites during heat exposure.

1. The chloramine-T procedure was employed to radio-iodinate cholera toxin using Na¹²⁵I. The procedure was found to be efficient and reproducible.

2. Intragastric injections of both the labelled and the unlabelled toxin produced (a) significant increases in intestinal fluid accumulation as measured by the fluid accumulation ratio; (b) significant increases in cAMP levels; and (c) significant decreases in cAMP-phosphodiesterase activities when compared with the controls suggesting that radio-iodination did not impair the biological activity of the toxin.

3. In vivo uptake studies of the labelled toxin by different parts of the intestine indicated that the uptake by the duodenum and jejunum was high and rapid when compared with the ileum implying that there are more binding sites (or receptor proteins) for cholera toxin in the duodenum and jejunum than in the ileum.

1. Amitraz stimulated [³H]batrachotoxin in A 20-α-benzoate ([³H]BTX-B) binding to neural membranes from pyrethroid susceptible (S) and resistant (R) tobacco budworm moths, but N′-(2,4-xylyl)-N-methylformamidine (SN 49844) stimulated binding only with S moths.

2. Chlordimeform stimulated [³H]BTX-B binding only with R moths, and N-(4-chloro-o-tolyl)-N-methylformamidine (demethylchlordimeform) yielded no significant stimulation with either strain.

3. A mixture of amitraz and deltamethrin, a pyrethroid that previously had been shown to enhance [³H]BTX-B binding with tobacco budworm moths, also gave significant stimulation of radioligand binding with S moths.

4. When membranes were prepared from S moths at various intervals following topical application of amitraz, deltamethrin, or a mixture of amitraz and deltamethrin, biphasic stimulation of [³H]BTX-B binding was observed, with maximum enhancement occurring at 2 and 6 hr.

5. These results provided a basis for suggesting that a formamidine binding site is located on or closely associated with the sodium channel protein.

6. Whether this site is the same as the pyrethroid/DDT binding domain remains to be demonstrated; however, similarities in responses elicited by amitraz and deltamethrin alone and in combination indicate that some relationship may exist.

1. Carp (Cyprinus carpio) and tilapia (Oreochromis mossambicus) were kept in a flow-through respirometer for a week, while continuous oxygen consumption measurements were carried out, at a constant water O₂ concentration.

2. Our measurements showed that tilapia decreased its standard metabolic rate (SMR), its average oxygen consumption, and its maximum metabolic rate in acid water (pH 4.0), whereas carp did not.

3. It is proposed, based on our results, that carp and tilapia probably have different strategies to survive pH depression episodes: whereas tilapia avoids the additional stress of exercise, carp tries to escape the acid conditions.

1. Effects of the following PRLamide peptides on some invertebrate muscles were examined: APNFLAYPRLamide (a peptide of the bivalve mollusc Mytilus), AAPLPRLamide (a peptide of the echiuroid Urechis), FTPRLamide (a fragment of a peptide of the insect Pseudaletia), YFSPRLamide (a fragment of a peptide of the insect Heliothis) and pQTSFTPRLamide (a peptide of the insect Leucophaea).

2. In the ABRM of Mytilus, the Mytilus and Urechis peptides potentiated phasic contraction by repetitive electrical stimulation. The former was more potent than the latter. The three insect-origin peptides did not show any potentiating effect but showed a weak antagonistic action on the potentiating effect of the Mytilus peptide. Except the Mytilus peptide, the PRLamide peptides showed little or no relaxing effect on catch tension, though they accelerated catch-relaxing response to repetitive electrical stimulation.

3. In the inner circular body-wall of muscle of Urechis, the PRLamide peptides showed a potentiating effect on twitch contraction. The Urechis peptide was most potent. In the esophagus of the annelid Perinereis, the PRLamide peptides showed a contractile effect. The Urechis peptide was also most potent.

4. In the crop of the cricket Gryllus, the insect-origin peptides markedly potentiated spontaneous rhythmic contractions. The Mytilus peptide showed a weak potentiating effect, but the Urechis peptide showed little or no effect.

1. The main objectives of the present study were to investigate the effects of either caffeine or ryanodine on action potential shape in four identified neurones of Lymnaea stagnalis (L) in situ.

2. The action potential width at half-amplitude (half-width, HW) is a Ca²⁺ -dependent phenomenon and hence it was used here as a measure of spike broadening or narrowing. Spike data were analysed using a computer programme and appropriate statistical tests were performed.

3. Intracellular recordings were made under control conditions to establish the frequency/HW relationship for each cell type. Recordings were also made from each cell after perfusion with two concentrations of each drug and their effects on the frequency/HW relationship were studied.

4. Caffeine produced a significant increase in HW in three out of four studied neurones, whilst ryanodine produced a significant response in only one neurone and inconsistent results in the remainder. Therefore, both drugs were found to produce cell specific responses.

5. The data presented here are consistent with previous studies which demonstrate that both caffeine and ryanodine act as mobilizing agents for intracellular calcium from internal storage sites, although by different mechanisms.

1. The catecholamine content in six endemic turbellarians of Lake Baikal was examined with high pressure liquid chromatography (HPLC).

2. The planarians Archicotylus sp., Baikalobia sp., Bdellocephala angarensis, Rimacephalus arecepta, Sorocelis nigrofasciata and the lecithoepitheliat Geocentrophora wagini were analysed.

3. Dopa and dopamine (DA) were detected in all species and noradrenaline was detected in all species except Archicotylus. DA dominates in all species.

4. Neither adrenaline nor the DA-metabolite DOPAC were detected.