Biogenic amines modulate pulse rate in the dorsal blood vessel of Lumbriculus variegatus.

The biogenic amines are widespread regulators of physiological processes, and play an important role in regulating heart rate in diverse organisms. Here, we present the first pharmacological evidence for a role of the biogenic amines in the regulation of dorsal blood vessel pulse rate in an aquatic oligochaete, Lumbriculus variegatus (Müller, 1774). Bath application of octopamine to intact worms resulted in an acceleration of pulse rate, but not when co-applied with the adenylyl cyclase inhibitor MDL-12,330a.

Demographic and random amplified polymorphic DNA analyses reveal high levels of genetic diversity in a clonal violet.

We performed demographic and molecular investigations on woodland populations of the clonal herb Viola riviniana in central Germany. We investigated the pattern of seedling recruitment, the amount of genotypic (clonal) variation and the partitioning of genetic variation among and within populations. Our demographic study was carried out in six violet populations of different ages and habitat conditions.

Inhibition of histamine secretion from mast cells by lipoxygenase- and cyclooxygenase inhibitors.

We have investigated the effect of inhibitors of lipoxygenase (LOX), cyclooxygenase (COX) and dual inhibitors of both enzymes on the degranulation of peritoneal rat mast cells (pRMC) activated by different mechanisms. COX inhibitors weakly affected histamine secretion induced by A23187 and did not influence the histamine secretion induced by protamine in an isotonic medium but blocked protamine-induced release in a hypertonic medium. LOX- and dual-inhibitors inhibited secretion induced by A23187 and protamine under all conditions.

PAF-induced death in NMRI mice--a suitable shock model for testing new PAF receptor antagonists. Correlation with eicosanoid related substances.

The effects of PAF antagonists, of substances which influence the arachidonic acid metabolism, and of dexamethasone and ketotifen were evaluated in an acute PAF-induced mortality model in female NMRI mice. We established a dependence of sensitivity to PAF on strain (AB mice showed no dose dependence) and on sex of the animals as well as on the PAF charges used in our experiments. PAF produced resistance in surviving animals against the PAF-induced death on repeated application.

[PAF-antagonists with a phospholipid structure. 5. Propanediol phospholipids with various substituted pyridinium and quinuclidinium head groups and variations of the phosphorus-nitrogen distance;synthesis, characterization and structure activity relationship].

A series of 10 PAF-analogues, structurally modified in position C-2 (n-propyl) and position C-3 (polar head group) were synthesized, and the PAF-inhibitory potencies was evaluated using PAF-induced aggregation of human blood platelets in vitro. Structure-activity relationships revealed, that the PAF-inhibitory activity is strongly influenced by the distance between phosphate and onium center and the structure of the substituted heterocyclus. The best activity was observed by 3,5-dimethylpyridinium- and 4-ethylpyridinium derivative with a P-N-distance of 6 methylene groups (IC50 = 1.