Guinea-pig Vocalizations: Their Structure, Causation and Function

We examined the impact of parainfluenza-3 (P-3) respiratory tract viral infection on the density and function of endothelin (ET) receptor subtypes (ETA and ETB) in guinea pig tracheal smooth muscle. Total specific binding of [125I]ET-1 and the relative proportions of ETA and ETB binding sites for this ligand were assessed at day 0 (control) and at 2, 4, 8 and 16 days post-inoculation. At day 0, the proportions of ETA and ETB binding sites were 30% and 70% respectively. Total specific binding was significantly reduced at day 4 post-inoculation (32% reduction, n = 8–12, P<0.05) and was largely due to a corresponding fall in ETB receptor density at this time point (38% reduction, n = 8–12, P<0.05). The density of ETA receptors also fell significantly at day 8 post-inoculation (33% reduction, n = 6–12, P<0.05). By day 16 post-inoculation, the densities of ETA and ETB receptors had recovered to control values. The ratio of ETA:ETB receptor subtypes did not alter with P-3 infection. While P-3 infection reduced the density of tracheal smooth muscle ETA and ETB receptors, the contractile sensitivity and maximum response to carbachol and ET-1 was not altered in tissue from day 4 post-inoculation compared with the control. There seems to be a significant functional reserve for both receptor subtypes in this species that buffers the impact of P-3 infection on airway smooth muscle responsiveness to ET-1.

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Phospholipid synthesis in HeLa cells exposed to immunoglobulin G and complement

Biochemical Journal ◽

10.1042/bj1280953 ◽

1972 ◽

Vol 128 (4) ◽

pp. 953-960 ◽

Cited By ~ 6

Author(s):

Flemming Güttler

Keyword(s):

Guinea Pig ◽

Hela Cells ◽

Immunoglobulin G ◽

Phospholipid Content ◽

Phospholipid Synthesis ◽

Twofold Increase ◽

And Function ◽

Phosphate Incorporation ◽

Pig Serum ◽

Stimulation Of

1. HeLa cells were cultured in the presence of heterologous immunoglobulin G and guinea-pig serum together with [32P]phosphate. 2. Incorporation of [32P]phosphate was significantly stimulated by anti-HeLa immunoglobulin G and complement-sufficient serum compared with immunoglobulin G from unimmunized rabbits and complement. Within 2.5h heat-inactivated guinea-pig serum and anti-HeLa immunoglobulin G stimulated [32P]phosphate incorporation to the same extent as heat-inactivated complement and immunoglobulin G from unimmunized rabbits. 3. Compared with cells exposed to immunoglobulin G from unimmunized rabbits together with complement, anti-HeLa immunoglobulin G with complement increased the phospholipid content of HeLa cells twofold within 5h of incubation. 4. Exposure of HeLa cells to anti-HeLa immunoglobulin G and complement for 5–22h resulted in a twofold increase in the net accumulation of [32P]phosphate in sphingomyelin and phosphatidylcholine and a 50% increase in the net accumulation of [32P]phosphate in phosphatidylethanolamine, compared with cultures exposed to immunoglobulin G from unimmunized rabbits and complement. 5. A transient accumulation of 32P-labelled lysophosphoglycerides in HeLa cells exposed to antibody and complement was detected, confirming previous findings (Güttler & Clausen, 1969b). 6. The stimulation of [32P]phosphate turnover occurred in cells filling up their cytoplasma with vacuoles. This supports the suggestion that the accumulation of phospholipid in these cells may be concerned with the synthesis and function of cytomembranes.

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Bioorganic studies on the venom from duckbill platypus

Pure and Applied Chemistry ◽

10.1351/pac-con-11-08-18 ◽

2012 ◽

Vol 84 (6) ◽

pp. 1317-1328 ◽

Cited By ~ 2

Author(s):

Masaki Kita

Keyword(s):

Molecular Weight ◽

Guinea Pig ◽

Structure And Function ◽

Low Molecular Weight ◽

Tissue Kallikrein ◽

Guinea Pig Ileum ◽

Porcine Pancreas ◽

Human Neuroblastoma ◽

Ornithorhynchus Anatinus ◽

And Function

Venomous mammals are rare, and only a few species in the orders Insectivora and Monotremata produce toxic venom. Among them, the duckbill platypus (Ornithorhynchus anatinus) is one of the two venomous Australian mammals. The adult male platypus carries a spur on each hind leg, which it uses to inject competitors with poison. However, the structure and function of the poison’s active compounds are still imcompletely characterized. We found that crude platypus venom produced potent Ca2+influx in human neuroblastoma IMR-32 cells. Guided by this assay, we identified 11 unique peptides, including peptide H–His–Asp–His–Pro–Asn–Pro–Arg–OH, which coincided with the N-terminal domain residues ofOrnithorhynchusvenom C-type natriuretic peptide (OvCNP). This heptapeptide induced a significant increase in [Ca2+]iin IMR-32 cells at 75 μM; had relatively specific affinities for glutamate, histamine, and GABAAreceptors; and facilitated neurogenic twitching in guinea pig ileum specimens at 30 μM. We also established that its proteinous venom fraction strongly hydrolyzed Pro–Phe–Arg–MCA and cleaved a human low-molecular-weight kininogen (LK), similar to porcine pancreas kallikrein. These results strongly indicated that platypus venom contains tissue kallikrein-like protease(s), and its proteolytic activity might synergistically contribute to toxicity through the specific cleavage of other venom constituents.

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Functional differences of Na+/Ca2+ exchanger expression in Ca2+ transport system of smooth muscle of guinea pig stomach

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y05-079 ◽

2005 ◽

Vol 83 (8-9) ◽

pp. 791-797 ◽

Cited By ~ 6

Author(s):

Yasushi Sakai ◽

Hiroki Kinoshita ◽

Keiichirou Saitou ◽

Ikuo Homma ◽

Koji Nobe ◽

...

Keyword(s):

Smooth Muscle ◽

Plasma Membrane ◽

Guinea Pig ◽

Gastric Fundus ◽

Relaxation Cycle ◽

Gastric Smooth Muscle ◽

Guinea Pig Stomach ◽

And Function ◽

The Relationship ◽

Ionophore Monensin

The plasma membrane ATP-dependent Ca2+ pump and the Na+/Ca2+ exchanger (NCX) are the major means of Ca2+ extrusion in smooth muscle. However, little is known regarding distribution and function of the NCX in guinea pig gastric smooth muscle. The expression pattern and distribution of NCX isoforms suggest a role as a regulator of Ca2+ transport in cells. Na+ pump inhibition and the consequent to removal of K+ caused gradual contraction in fundus. In contrast, the response was significantly less in antrum. Western blotting analysis revealed that NCX1 and NCX2 are the predominant NCX isoforms expressed in stomach, the former was expressed strongly in antrum, whereas the latter displayed greater expression in fundus. Isolated plasma membrane fractions derived from gastric fundus smooth muscle were also investigated to clarify the relationship between NCX protein expression and function. Na+-dependent Ca2+ uptake increased directly with Ca2+ concentration. Ca2+ uptake in Na+-loaded vesicles was markedly elevated in comparison with K+-loaded vesicles. Additionally, Ca2+ uptake by the Na+- or K+-loaded vesicles was substantially higher in the presence of A23187 than in its absence. The result can be explained based on the assumption that Na+ gradients facilitate downhill movement of Ca2+. Na+-dependent Ca2+ uptake was abolished by the monovalent cationic ionophore, monensin. NaCl enhanced Ca2+ efflux from vesicles, and this efflux was significantly inhibited by gramicidin. Results documented evidence that NCX2 isoform functionally contributes to Ca2+ extrusion and maintenance of contraction-relaxation cycle in gastric fundus smooth muscle.Key words: stomach, smooth muscle, Na+/Ca2+ exchanger (NCX), NCX2.

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