Electrophysiological Properties of Ion Channels in Ascaris suum Tissue Incorporated into Planar Lipid Bilayers.

Ion channels are important targets of anthelmintic agents. In this study, we identified 3 types of ion channels in Ascaris suum tissue incorporated into planar lipid bilayers using an electrophysiological technique. The most frequent channel was a large-conductance cation channel (209 pS), which accounted for 64.5% of channels incorporated (n=60). Its open-state probability (Po) was ~0.3 in the voltage range of -60~+60 mV. A substate was observed at 55% of the main-state. The permeability ratio of Cl- to K+ (PCl/PK) was ~0.5 and PNa/PK was 0.81 in both states. Another type of cation channel was recorded in 7.5% of channels incorporated (n=7) and discriminated from the large-conductance cation channel by its smaller conductance (55.3 pS). Its Po was low at all voltages tested (~0.1). The third type was an anion channel recorded in 27.9% of channels incorporated (n=26). Its conductance was 39.0 pS and PCl/PK was 8.6±0.8. Po was ~1.0 at all tested potentials. In summary, we identified 2 types of cation and 1 type of anion channels in Ascaris suum. Gating of these channels did not much vary with voltage and their ionic selectivity is rather low. Their molecular nature, functions, and potentials as anthelmintic drug targets remain to be studied further.

Acute Anemia Induces Erythropoiesis in Rat Organ Surface Primo-Vascular Tissue.

The primo-vascular system (PVS) is a newly identified vascular tissue composed of primo-nodes (PNs) and primo-vessels (PVs). Previously, we reported erythropoietic activity in the organ-surface PVS (osPVS) tissue of rats with heart failure. In this study, we further investigated whether acute anemia could induce erythropoiesis in the PVS of rats, based on the hypothesis that erythropoiesis in osPVS tissue is due to anemia accompanying heart failure. Acute anemia was induced by an intraperitoneal injection of phenylhydrazine (PHZ). Circulating red blood cells (RBCs) and hematocrit decreased by 31.6%, whereas reticulocytes and white blood cells increased at day 3 and day 6 after PHZ treatment. All these parameters recovered to control levels at day 10. At days 3 and 6, we observed an increase in the size of the PNs (P < 0.05), the number of the osPVS tissue samples per rat (P < 0.01), and the proportion of osPVS tissue samples with red chromophore (P < 0.001), which was from the RBCs in the PVS tissue. The number of RBCs, estimated from the PN sections stained with hematoxylin and eosin, increased at day 6 in the rats with anemia (P < 0.01). All these anemia-induced changes in the osPVS tissue recovered to the control levels by day 10. Taken together, the results showed that the morphological and cytological changes in the osPVS tissue appear to be related to the erythropoietic activity induced by acute anemia in rats. This study confirmed the previous findings that the osPVS can exert erythropoietic activity in disease states accompanied by anemia, such as heart failure.

Physicochemical factors that affect electroporation of lung cancer and normal cell lines.

Electroporation is used for cancer therapy to efficiently destroy cancer tissues by transferring anticancer drugs into cancer cells or by irreversible tumor ablation without resealing pores. There is growing interest in the electroporation method for the treatment of lung cancer, which has the highest mortality rate among cancers. Improving the cancer cell selectivity has the potential to expand its use. However, the factors that influence the cell selectivity of electroporation are debatable. We aimed to identify the important factors that influence the efficiency of electroporation in lung cells. The electropermeabilization of lung cancer cells (H460, A549, and HCC1588) and normal lung cells (MRC5, WI26 and L132) was evaluated by the transfer of fluorescence dyes. We found that membrane permeabilization increased as cell size, membrane stiffness, resting transmembrane potential, and lipid cholesterol ratio increased. Among them, lipid composition was found to be the most relevant factor in the electroporation of lung cells. Our results provide insight into the differences between lung cancer cells and normal lung cells and provide a basis for enhancing the sensitivity of lung cancers cells to electroporation.

Exercise training normalizes elevated firing rate of hypothalamic presympathetic neurons in heart failure rats.

Exercise training (ExT) normalizes elevated sympathetic nerve activity in heart failure (HF), but the underlying mechanisms are not well understood. In this study, we examined the effects of 3 wk of ExT on the electrical activity of the hypothalamic presympathetic neurons in the brain slice of HF rats. HF rats were prepared by ligating the left descending coronary artery. The electrophysiological properties of paraventricular nucleus neurons projecting to the rostral ventrolateral medulla (PVN-RVLM) were examined using the slice patch-clamp technique. The neuronal firing rate was elevated in HF rats, and ExT induced a reduction in the firing rate ( P < 0.01). This ExT-induced decrease in the firing rate was associated with an increased frequency of spontaneous and miniature inhibitory postsynaptic current (IPSCs; P < 0.05). There was no significant change in excitatory postsynaptic current. Replacing Ca2+ with Mg2+ in the recording solution reduced the elevated IPSC frequency in HF rats with ExT ( P < 0.01) but not in those without ExT, indicating an increase in the probability of GABA release. In contrast, ExT did not restore the reduced GABAA receptor-mediated tonic inhibitory current in HF rats. A GABAA receptor blocker (bicuculline, 20 µM) increased the firing rate in HF rats with ExT ( P < 0.01) but not in those without ExT. Collectively, these results show that ExT normalized the elevated firing activity by increasing synaptic GABA release in PVN-RVLM neurons in HF rats. Our findings provide a brain mechanism underlying the beneficial effects of ExT in HF, which may shed light on the pathophysiology of other diseases accompanied by sympathetic hyperactivation.

Alteration of MicroRNA Expression Profiles by Surface-Modified Gold Nanoparticles in Human Lung Adenocarcinoma Cells.

MicroRNAs that bind to mRNA are important post-transcriptional regulators that control gene expression by degradation or suppressing translation of target mRNAs. Several studies indicate that nanoparticles (NPs) induce alterations in microRNA expression relating to cell processes including cell development and progressive diseases. However, the alteration of microRNA expression by surface-modified gold nanoparticles (AuNPs) in A549 cells has not been reported. In order to investigate the patterns of microRNA expression, we analyzed data from microRNA arrays using cells treated with citrate- or chitosan-AuNPs. The results demonstrate that the expression of microRNA (hsa-miR-198) in cells treated with citrate-AuNPs significantly differed from non-treated cells, and the expression of 16 microRNAs in cells treated with chitosan-AuNPs significantly differed from non-treated cells. Furthermore, the predicted target genes of microRNAs were related to proliferation, apoptosis, migration, and cell differentiation, including the mitogen-activated protein kinase, ErbB, and Wnt signaling pathway. Thus, the alteration of microRNA expression profiles by citrate- and chitosan-AuNPs would mediate the regulation of the cell processes including cell survival, migration, and differentiation.

Immunological responses against vancomycin-resistant Enterococcus faecium and Enterococcus faecalis by mice.

Methicillin-resistant Staphylococcus aureus (MRSA) infections in humans can currently only be treated with vancomycin. Consequently, vancomycin-resistant Enterococcus spp. pose a serious public health hazard because MRSA can acquire their vancomycin resistance. While the microbiological and genetic characteristics of vancomycin-resistant enterococci (VRE) have been extensively studied, serological diagnostic tools for these organisms are lacking. The VanA and VanB classes of VRE show marked resistance. Here, we identified the VanA and VanB proteins that are immunogenic in mice. To do so, mice were orally infected with a VanA strain of E. faecium or a VanB strain of E. faecalis and the serologically immunogenic proteins were identified by SDS-PAGE and Western blot analysis. The mice reacted to the 27 and 65 kDa cell envelope (CE) proteins of VanA at 1 week post-infection (wpi) and then reacted to the 100 kDa cytoplasmic protein (CP) at 2-4 wpi. With regard to VanB, the mice responded at 1-4 wpi, 3-4 wpi, and 4 wpi to the 70 kDa, 25 and 35 kDa, and 79 kDa CE proteins, respectively, and at 3 wpi to the 39 kDa CP. The identification of these immunogenic proteins may be useful for diagnosing and for producing immunotherapeutic VRE antibodies.

Kv3.1 and Kv3.4, Are Involved in Cancer Cell Migration and Invasion.

Voltage-gated potassium (Kv) channels, including Kv3.1 and Kv3.4, are known as oxygen sensors, and their function in hypoxia has been well investigated. However, the relationship between Kv channels and tumor hypoxia has yet to be investigated. This study demonstrates that Kv3.1 and Kv3.4 are tumor hypoxia-related Kv channels involved in cancer cell migration and invasion. Kv3.1 and Kv3.4 protein expression in A549 and MDA-MB-231 cells increased in a cell density-dependent manner, and the pattern was similar to the expression patterns of hypoxia-inducible factor-1α (HIF-1α) and reactive oxygen species (ROS) according to cell density, whereas Kv3.3 protein expression did not change in A549 cells with an increase in cell density. The Kv3.1 and Kv3.4 blocker blood depressing substance (BDS) did not affect cell proliferation; instead, BDS inhibited cell migration and invasion. We found that BDS inhibited intracellular pH regulation and extracellular signal-regulated kinase (ERK) activation in A549 cells cultured at a high density, potentially resulting in BDS-induced inhibition of cell migration and invasion. Our data suggest that Kv3.1 and Kv3.4 might be new therapeutic targets for cancer metastasis.

Potential Erythropoiesis in the Primo-Vascular System in Heart Failure.

The primo-vascular system (PVS), composed of primo-nodes (PNs) and primo-vessels (PVs), has been identified in various animal models. However, little is known about its function. Here, we investigated the changes in gross morphology and cellular composition of the organ-surface PVS (osPVS) in rats with heart failure (HF) induced by myocardial infarction. The size of the PNs in rats with HF was larger than in sham rats (1.87 vs. 0.80 mm2; P < 0.01) and the density of osPVS per rat was greater for the HF rats (28 of 6 rats vs. 19 of 9 rats; P < 0.01). In addition, the osPVS number containing red chromophore was greater in HF rats (P < 0.001). The chromophore was identified as hemoglobin. Transmission electron microscopy and H&E staining revealed that the osPVS of HF rats (P < 0.001) possessed more red blood cells (RBCs) than that of the sham rats. In particular, immature RBC number increased in the HF rats (90.7 vs. 42.3%; P < 0.001). Altogether, the results showed that the osPVS in HF rats increased in its size, density, and the proportion of immature RBCs in the PNs, which may indicate that the PVS has erythropoietic activity. Our study will help to elucidate the physiological roles of PVS in normal and disease states associated with HF.

Nuclear localization and functional characteristics of voltage-gated potassium channel Kv1.3.

It is widely known that ion channels are expressed in the plasma membrane. However, a few studies have suggested that several ion channels including voltage-gated K(+) (Kv) channels also exist in intracellular organelles where they are involved in the biochemical events associated with cell signaling. In the present study, Western blot analysis using fractionated protein clearly indicates that Kv1.3 channels are expressed in the nuclei of MCF7, A549, and SNU-484 cancer cells and human brain tissues. In addition, Kv1.3 is located in the plasma membrane and the nucleus of Jurkat T cells. Nuclear membrane hyperpolarization after treatment with margatoxin (MgTX), a specific blocker of Kv1.3 channels, provides evidence for functional channels at the nuclear membrane of A549 cells. MgTX-induced hyperpolarization is abolished in the nuclei of Kv1.3 silenced cells, and the effects of MgTX are dependent on the magnitude of the K(+) gradient across the nuclear membrane. Selective Kv1.3 blockers induce the phosphorylation of cAMP response element-binding protein (CREB) and c-Fos activation. Moreover, Kv1.3 is shown to form a complex with the upstream binding factor 1 in the nucleus. Chromatin immunoprecipitation assay reveals that Sp1 transcription factor is directly bound to the promoter region of the Kv1.3 gene, and the Sp1 regulates Kv1.3 expression in the nucleus of A549 cells. These results demonstrate that Kv1.3 channels are primarily localized in the nucleus of several types of cancer cells and human brain tissues where they are capable of regulating nuclear membrane potential and activation of transcription factors, such as phosphorylated CREB and c-Fos.

Ultrastructure of the Subcutaneous Primo-Vascular System in Rat Abdomen.

Recently, we identified the primo-vascular system (PVS), a novel vascular network, in rat subcutaneous tissues. Little is known about the subcutaneous PVS (sc-PVS). Here, we examined the ultrastructure of the sc-PVS in the hypodermis at the rat abdominal midline by electron microscopy. On the surface of sc-PVS, we observed three types of cells: microcells (5-6 µm), large elliptical cells (>20 µm), and erythrocyte (3-4 µm). The inside of the sc-PVS was filled with numerous cells, which can be classified into three major groups: leucocytes, mast cells, and erythrocytes. The dense leucocytes and mast cells were easily noticed. The extracellular matrix of the sc-PVS was mainly composed of extensive fibers (79 ± 6.5 nm) tightly covered by micro- (0.5-1 µm) and nanoparticles (10-100 nm). In conclusion, the ultrastructural features, such as the resident cells on and in the sc-PVS and fiber meshwork covered by particles, indicate that sc-PVS might act as a circulatory channel for the flow and delivery of numerous cells and particles. Our findings will help understand the nature of various sc-PVS beneath-the-skin layers and how they relate to acupuncture meridians.

The Role of KV7.3 in Regulating Osteoblast Maturation and Mineralization.

KCNQ (KV7) channels are voltage-gated potassium (KV) channels, and the function of KV7 channels in muscles, neurons, and sensory cells is well established. We confirmed that overall blockade of KV channels with tetraethylammonium augmented the mineralization of bone-marrow-derived human mesenchymal stem cells during osteogenic differentiation, and we determined that KV7.3 was expressed in MG-63 and Saos-2 cells at the mRNA and protein levels. In addition, functional KV7 currents were detected in MG-63 cells. Inhibition of KV7.3 by linopirdine or XE991 increased the matrix mineralization during osteoblast differentiation. This was confirmed by alkaline phosphatase, osteocalcin, and osterix in MG-63 cells, whereas the expression of Runx2 showed no significant change. The extracellular glutamate secreted by osteoblasts was also measured to investigate its effect on MG-63 osteoblast differentiation. Blockade of KV7.3 promoted the release of glutamate via the phosphorylation of extracellular signal-regulated kinase 1/2-mediated upregulation of synapsin, and induced the deposition of type 1 collagen. However, activation of KV7.3 by flupirtine did not produce notable changes in matrix mineralization during osteoblast differentiation. These results suggest that KV7.3 could be a novel regulator in osteoblast differentiation.

Enhanced astroglial GABA uptake attenuates tonic GABAA inhibition of the presympathetic hypothalamic paraventricular nucleus neurons in heart failure.

γ-Aminobutyric acid (GABA) generates persistent tonic inhibitory currents (Itonic) and conventional inhibitory postsynaptic currents in the hypothalamic paraventricular nucleus (PVN) via activation of GABAA receptors (GABAARs). We investigated the pathophysiological significance of astroglial GABA uptake in the regulation of Itonic in the PVN neurons projecting to the rostral ventrolateral medulla (PVN-RVLM). The Itonic of PVN-RVLM neurons were significantly reduced in heart failure (HF) compared with sham-operated (SHAM) rats. Reduced Itonic sensitivity to THIP argued for the decreased function of GABAAR δ subunits in HF, whereas similar Itonic sensitivity to benzodiazepines argued against the difference of γ2 subunit-containing GABAARs in SHAM and HF rats. HF Itonic attenuation was reversed by a nonselective GABA transporter (GAT) blocker (nipecotic acid, NPA) and a GAT-3 selective blocker, but not by a GAT-1 blocker, suggesting that astroglial GABA clearance increased in HF. Similar and minimal Itonic responses to bestrophin-1 blockade in SHAM and HF neurons further argued against a role for astroglial GABA release in HF Itonic attenuation. Finally, the NPA-induced inhibition of spontaneous firing was greater in HF than in SHAM PVN-RVLM neurons, whereas diazepam induced less inhibition of spontaneous firing in HF than in SHAM neurons. Overall, our results showed that combined with reduced GABAARs function, the enhanced astroglial GABA uptake-induced attenuation of Itonic in HF PVN-RVLM neurons explains the deficit in tonic GABAergic inhibition and increased sympathetic outflow from the PVN during heart failure.

Low Non-NMDA Receptor Current Density as Possible Protection Mechanism from Neurotoxicity of Circulating Glutamate on Subfornical Organ Neurons in Rats.

The subfornical organ (SFO) is one of circumventricular organs characterized by the lack of a normal blood brain barrier. The SFO neurons are exposed to circulating glutamate (60~100 µM), which may cause excitotoxicity in the central nervous system. However, it remains unclear how SFO neurons are protected from excitotoxicity caused by circulating glutamate. In this study, we compared the glutamate-induced whole cell currents in SFO neurons to those in hippocampal CA1 neurons using the patch clamp technique in brain slice. Glutamate (100 µM) induced an inward current in both SFO and hippocampal CA1 neurons. The density of glutamate-induced current in SFO neurons was significantly smaller than that in hippocampal CA1 neurons (0.55 vs. 2.07 pA/pF, p<0.05). To further identify the subtype of the glutamate receptors involved, the whole cell currents induced by selective agonists were then compared. The current densities induced by AMPA (0.45 pA/pF) and kainate (0.83 pA/pF), non-NMDA glutamate receptor agonists in SFO neurons were also smaller than those in hippocampal CA1 neurons (2.44 pA/pF for AMPA, p<0.05; 2.34 pA/pF for kainate, p< 0.05). However, the current density by NMDA in SFO neurons was not significantly different from that of hippocampal CA1 neurons (1.58 vs. 1.47 pA/pF, p>0.05). These results demonstrate that glutamate-mediated action through non-NMDA glutamate receptors in SFO neurons is smaller than that of hippocampal CA1 neurons, suggesting a possible protection mechanism from excitotoxicity by circulating glutamate in SFO neurons.

Serum starvation-induced voltage-gated potassium channel Kv7.5 expression and its regulation by Sp1 in canine osteosarcoma cells.

The KCNQ gene family, whose members encode Kv7 channels, belongs to the voltage-gated potassium (Kv) channel group. The roles of this gene family have been widely investigated in nerve and muscle cells. In the present study, we investigated several characteristics of Kv7.5, which is strongly expressed in the canine osteosarcoma cell line, CCL-183. Serum starvation upregulated Kv7.5 expression, and the Kv7 channel opener, flupirtine, attenuated cell proliferation by arresting cells in the G0/G1 phase. We also showed that Kv7.5 knockdown helps CCL-183 cells to proliferate. In an effort to find an endogenous regulator of Kv7.5, we used mithramycin A to reduce the level of the transcription factor Sp1, and it strongly inhibited the induction of Kv7.5 in CCL-183 cells. These results suggest that the activation of Kv7.5 by flupirtine may exert an anti-proliferative effect in canine osteosarcoma. Therefore, Kv7.5 is a possible molecular target for canine osteosarcoma therapy.

Dual mechanisms diminishing tonic GABAA inhibition of dentate gyrus granule cells in Noda epileptic rats.

The Noda epileptic rat (NER), a Wistar colony mutant, spontaneously has tonic-clonic convulsions with paroxysmal discharges. In the present study, we measured phasic and tonic γ-aminobutyric acid A (GABAA) current (I tonic) in NER hippocampal dentate gyrus granule cells and compared the results with those of normal parent strain Wistar rats (WIS). I tonic, revealed by a bicuculline-induced outward shift in holding current, was significantly smaller in NER than in WIS (P < 0.01). The frequency of inhibitory postsynaptic currents (IPSCs) was also significantly lower in NER than in WIS (P < 0.05), without significant differences in the IPSC amplitude or decay time between WIS and NER. I tonic attenuation in NER was further confirmed in the presence of GABA transporter blockers, NO-711 and nipecotic acid, with no difference in neuronal GABA transporter expression between WIS and NER. I tonic responses to extrasynaptic GABAA receptor agonists (THIP and DS-2) were significantly reduced in NER compared with WIS (P < 0.05). Allopregnanolone caused less I tonic increase in NER than in WIS, while it prolonged the IPSC decay time to a similar rate in the two groups. Expression of the GABAA receptor δ-subunit was decreased in the dentate gyrus of NER relative to that of WIS. Taken together, our results showed that a combination of attenuated presynaptic GABA release and extrasynaptic GABAA receptor expression reduced I tonic amplitude and its sensitivity to neurosteroids, which likely diminishes the gating function of dentate gyrus granule cells and renders NER more susceptible to seizure propagation.

Estrogen replacement modulates voltage-gated potassium channels in rat presympathetic paraventricular nucleus neurons.

BACKGROUND: The hypothalamic paraventricular nucleus (PVN) is an important site in the regulation of the autonomic nervous system. Specifically, PVN neurons projecting to the rostral ventrolateral medulla (PVN-RVLM) play a regulatory role in the determination of the sympathetic outflow in the cardiovascular system. In the PVN-RVLM neurons, the estrogen receptor ß is expressed. However, to date, the effects of estrogen on PVN-RVLM neurons have not been reported. The present study investigated estrogen-mediated modulation of two voltage-gated potassium channel (Kv) subunits, Kv4.2 and Kv4.3, that are expressed predominantly in PVN neurons and the functional current of Kv4.2 and Kv4.3, the transient outward potassium current (IA). RESULTS: Single-cell real-time RT-PCR analysis showed that 17ß-estradiol (E2) replacement (once daily for 4 days) selectively down-regulated Kv4.2 mRNA levels in the PVN-RVLM neurons of ovariectomized female rats. There was no change in Kv4.3 levels. Whole-cell patch-clamp recordings demonstrated that E2 also diminished IA densities. Interestingly, these effects were most apparent in the dorsal cap parvocellular subdivision of the PVN. E2 also shortened a delay in the excitation of the PVN-RVLM neurons. CONCLUSIONS: These findings demonstrate that E2 exerts an inhibitory effect on the functions of IA, potentially by selectively down-regulating Kv4.2 but not Kv4.3 in PVN-RVLM neurons distributed in a specific parvocellular subdivision.

Voltage-gated K+ channels in adipogenic differentiation of bone marrow-derived human mesenchymal stem cells.

AIM: To determine the presence of voltage-gated K(+) (Kv) channels in bone marrow-derived human mesenchymal stem cells (hMSCs) and their impact on differentiation of hMSCs into adipocytes. METHODS: For adipogenic differentiation, hMSCs were cultured in adipogenic medium for 22 d. The degrees of adipogenic differentiation were examined using Western blot, Oil Red O staining and Alamar assay. The expression levels of Kv channel subunits Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv2.1, Kv3.1, Kv3.3, Kv4.2, Kv4.3, and Kv9.3 in the cells were detected using RT-PCR and Western blot analysis. RESULTS: The expression levels of Kv2.1 and Kv3.3 subunits were markedly increased on d 16 and 22. In contrast, the expression levels of other Kv channel subunits, including Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv4.2, Kv4.3, and Kv9.3, were decreased as undifferentiated hMSCs differentiated into adipocytes. Addition of the Kv channel blocker tetraethylammonium (TEA, 10 mmol/L) into the adipogenic medium for 6 or 12 d caused a significant decrease, although not complete, in lipid droplet formation and adipocyte fatty acid-binding protein 2 (aP(2)) expressions. Addition of the selective Kv2.1 channel blocker guangxitoxin (GxTX-1, 40 nmol/L) into the adipogenic medium for 21 d also suppressed adipogenic differentiation of the cells. CONCLUSION: The results demonstrate that subsets of Kv channels including Kv2.1 and Kv3.3 may play an important role in the differentiation of hMSCs into adipocytes.

Establishing veterinary graduation competencies and its impact on veterinary medical education in Korea.

Competencies are defined as an observable and assessable set of knowledge, skills, and attitudes. Graduation competencies, which are more comprehensive, refer to the required abilities of students to perform on-site work immediately after graduation. As graduation competencies set the goal of education, various countries and institutions have introduced them for new veterinary graduates. The Korean Association of Veterinary Medical Colleges has recently established such competencies to standardize veterinary education and enhance quality levels thereof. The purpose of this study is to describe the process of establishing graduation competencies as well as their implication for veterinary education in Korea. Graduation competencies for veterinary education in Korea comprise 5 domains (animal health care and disease management, one health expertise, communication and collaboration, research and learning, and veterinary professionalism). These are further divided into 11 core competencies, and 33 achievement standards, which were carefully chosen from previous case analyses and nation-wide surveys. Currently, graduation competencies are used as a standard for setting clear educational purposes for both instructors and students. Establishing these competencies further initiated the development of detailed learning outcomes, and of a list of basic veterinary clinical performances and skills, which is useful for assessing knowledge and skills. The establishment of graduation competencies is expected to contribute to the continuous development of Korean veterinary education in many ways. These include curriculum standardization and licensing examination reform, which will eventually improve the competencies of new veterinary graduates.

Adrenergic Control of Primo Tissue Size in Rats.

Background: Hyperplastic morphological changes associated with erythropoiesis have been reported in the primo vascular system (PVS) tissue on the surface of abdominal organs in rats with heart failure (HF) or hemolytic anemia (HA). Objectives: Since adrenergic activity is commonly activated in both HF and HA, we investigated whether adrenergic signaling mediates the abovementioned morphological changes. Methods: We compared the effects of adrenolytic treatments (exercise training and 6-hydroxydopamine) on the gross morphology of the PVS tissues isolated from organ surfaces in HF or HA rats. HF and HA were induced by ligating the left coronary artery and injecting phenylhydrazine, respectively. We further compared the effects of norepinephrine and norepinephrine plus α- or ß-adrenoceptor blockers. Results: The number of samples per rat, PN size, and proportion of red-colored samples in the PVS tissue increased in the HF and HA rats. These changes were reversed by adrenolytic treatments. Interestingly, 6-hydroxydopamine also reversed phenylhydrazineinduced hemolytic changes in erythrocytes. Subcutaneous administration of norepinephrine (3 mg/kg/d) increased the sampling frequency per rat and the PN size, but these effects were blunted at a higher dose (10 mg/kg/d). Norepinephrine administration had little effect on the proportion of red-colored tissues. Norepinephrine-induced morphological changes were completely blocked by a ß-adrenoceptor antagonist (propranolol) but increased slightly by an α-adrenoceptor antagonist (phentolamine). Conclusion: Adrenergic signaling controls hyperplastic changes in the organ surface PVS in rats. These findings may explain the morphological dynamics of the PVS tissues proposed by Bong Han Kim and further clarify the pathophysiological roles of the PVS.