卷 54, 编号 1 (2018)

The review summarizes data on the number, size and localization of serotoninergic neurons in cercariae of 16 trematode species, referring to 11 families. Presented diagrams show distribution patterns of serotoninergic neurons in cercariae of trematodes from different taxonomic, biological and morphological groups. Data analysis indicates that the number, disposition and size of these neurons vary in cercariae of different species. The data are discussed in relation with a functional significance of serotonin as a neurotransmitter in free-living larvae—trematode cercariae.

We report a pioneering analysis of the interaction between mammalian cholinesterases and 36 acylates and thioacylates of ammonium alcohols with different structure of an alkyl chain between ammonium and etheric atoms and with different structure of a cyclic ammonium group. Among these ethers, which were both substrates and reversible inhibitors of erythrocyte cholinesterase and serum butyrylcholinesterase, specific effectors of both enzymes were identified.

Analysis of own and literature data shows that oxygen tension and mass transfer in skeletal muscles of higher and lower vertebrates (mammals, teleosts) are quite comparable. Oxygen consumption in fish muscles is 2–6 times lower and occurs at higher diffusion gradients of PO₂ (blood ↔ muscles: 45–57 hPa). Wei ghted mean values of PO₂ in fish muscles (with allowance for muscle composition) are minimum (5–12 hPa). As compared to mammals, they exhibit an extremely low diffusion capacity of the hematoparenchymal barrier (0.0014–0.0055 mLO₂ min^–1 100 g^–1 hPa^–1) which appears to rely on diffusion characteristics of cell membranes. Apparently, this is the main reason that accounts for low values of tissue PO₂ as well as low efficacy and oxygen utilization degree in muscles of this taxonomic group of animals.

The effect of histamine on background spontaneous electrical activity of the interrelated bladder and urethra was studied in rats. The basic characteristics of pacemaker activity (action potential amplitude, average peak rise rate, peak rise time, peak half-width, rhythmogenicity frequency) were analyzed both in normal conditions and upon exposure to histamine (10^–4 mol/L). A comparison of the action potential parameters in the above organs demonstrated far lower values of the amplitude (by 34.19%; p ≤ 0.001), peak rise rate (by 30.39%; p ≤ 0.01) and peak rise time (by 18%; p ≤ 0.01) at a reduced rhythmogenicity frequency. Histamine evoked a considerable increase in the amplitude and its rise rate in the bladder (by 50.59 and 56.36%, respectively; p ≤ 0.001) and rhythmogenicity frequency (by 18%; p ≤ 0.01) at a constancy of the remaining two parameters. In the urethra, no obvious changes were detected in the action potential parameters. Morphohistochemical analysis also supported the involvement of histamine in the activation of rhythmogenicity only in the bladder. Thus, histamine is not implicated in the genesis of tonic contractions in the urethra, in contrast to its activating effect on the bladder.

We report the results of our studies of the distribution patterns of calcium-binding proteins (parvalbumin, PV, and calbindin, CB) and metabolic activity (cytochrome oxidase, CO) in the pigeon entopallium—the telencephalic projection field of the tectofugal visual system. These characteristics were comparatively analyzed in different avian species in the light of the recent revision of entopallial projections’ nomenclature (Krützfeldt and Wild, 2005). We demonstrate that in the pigeon neuropil both high PV immunoreactivity and CO activity as well as lower CB immunoreactivity are confined to the core region of the entopallium (E). The latter contains cells immunoreactive (ir) to PV and CB and having a heterogenous repertoire: small/medium-sized granular and large multipolar cells. They overlap in E and partly colocalize within the same cell, but differ in the internal (Ei) and external (Ex) portions by distribution density and labeling intensity. CO activity was identified in both cellular morphotypes. Sparse PV- and CB-ir cells were found in the perientopallium (Ep). The interspecies variability of PV and CB immunoreactivity, described in the avian entopallium by other authors, indicates its dependence on the adaptive functional specialization which underlies selective expression of these calcium-binding proteins. The above as well as the pertinent literature data are discussed in the wake of the current discussion on homology of the avian entopallium, supporting the idea of the existence in sauropsid amniotes of the ancestral precursor of the mammalian extrastriate visual cortex.