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| 2. |
- Zygmunt, P.M., et al.
(författare)
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Effects of ω‐conotoxin on adrenergic, cholinergic and NANC neurotransmission in the rabbit urethra and detrusor
- 1993
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Ingår i: British Journal of Pharmacology. - : Wiley. - 0007-1188. ; 110:4, s. 1285-1290
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Tidskriftsartikel (refereegranskat)abstract
- The effects of ω‐conotoxin GVIA (an inhibitor of N‐type voltage‐operated calcium channels; VOCCs) were compared on adrenergic, cholinergic and non‐adrenergic, non‐cholinergic (NANC) responses induced by electrical field stimulation (EFS) in the rabbit urethra and detrusor. EFS induced a relaxation in urethral smooth muscle and lamina propria precontracted by arginine vasopressin (AVP). The relaxation was abolished by tetrodotoxin (TTX) or the nitric oxide (NO) synthase inhibitor Nω‐nitro‐l‐arginine. ω‐Conotoxin inhibited the relaxation induced by EFS, but not that elicited by the NO donor 3‐morpholino‐sydnonimin. The inhibition, however, decreased with increasing frequencies of stimulation. Nimodipine, tetramethrin and nickel did not affect the ω‐conotoxin‐resistant relaxation in lamina propria, suggesting that neuronal L or T VOCCs were not involved in the response. EFS contracted urethral smooth muscle at resting tension. The contractions were virtually abolished by TTX or prazosin. ω‐Conotoxin effectively inhibited the contractile responses to EFS, but not those to exogenous noradrenaline. An ω‐conotoxin‐resistant contraction was, however, observed at high frequencies of stimulation. The detrusor responded with frequency‐dependent contractions upon EFS. A TTX‐resistant contraction less than 10% of controls remained at 30 Hz stimulation. At a stimulation frequency of 10 Hz, scopolamine reduced the EFS‐induced contraction by 71%. ω‐Conotoxin inhibited the responses in both the absence and presence of scopolamine. The inhibition decreased with increasing frequencies of stimulation (examined in the absence of scopolamine). ω‐Conotoxin did not affect the contractile responses to carbachol or adenosine 5′‐triphosphate. The adrenergic contraction (25 Hz) and NANC relaxation (10 Hz) in the urethra, and cholinergic and NANC contractions (10 Hz) in the detrusor were inhibited concentration‐dependently by ω‐conotoxin. The adrenergic contraction in the urethra was 10 times and the cholinergic contraction in the detrusor was three times more sensitive to ω‐conotoxin than the NANC responses. These results suggest that NANC neurotransmission is less inhibited by ω‐conotoxin than transmission mediated by adrenergic and cholinergic nerves in the rabbit lower urinary tract. In the urethra a marked ω‐conotoxin‐resistant component of the NANC relaxation was observed which increased with increasing stimulation frequencies and was unaffected by inhibitors of L and T type VOCCs. This raises the question whether VOCCs of a type other than L, T, and N is involved in the mediation of this response. 1993 British Pharmacological Society
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| 3. |
- Degerman, Eva, et al.
(författare)
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Single-step affinity purification, partial structure and properties of human platelet cGMP inhibited cAMP phosphodiesterase
- 1994
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Ingår i: Biochimica et Biophysica Acta. - 0006-3002. ; 1205:2, s. 189-198
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Tidskriftsartikel (refereegranskat)abstract
- The human platelet cilostamide- and cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) was rapidly purified approximately 19,000-fold to apparent homogeneity using single step affinity chromatography on the isothiocyanate derivative of cilostamide coupled to aminoethyl agarose. Within 24 h, 30 micrograms of enzyme protein was obtained from 20 ml of packed platelets. Vmax for cAMP and cGMP was 6.1 and 0.9 mumol/min per mg protein, respectively. Several polypeptides (110/105, 79, 62, 55/53 kDa) were identified after SDS-PAGE, all of which were immunologically related to cGI-PDE and represented approx. 5, 20, 50 and 20% of the total protein, respectively. Limited proteolysis of the cGI-PDE with chymotrypsin produced a major fragment of approximately 47 kDa (and at least two smaller peptides) with catalytic activity and sensitivity to cGMP and OPC 3911 similar to controls. Phosphorylation of the cGI-PDE by cAMP-dependent protein kinase (A-kinase) resulted in maximal incorporation of 0.6-1.8 mol of 32P/mol 110/105 and 79 kDa polypeptides; much lower and variable amounts of phosphate were incorporated into the 62 and 55/53 kDa polypeptides. After digestion of cGI-PDE with several proteinases a number of peptides were isolated and sequenced. Most of the peptide sequences obtained could be aligned within the carboxy terminal domain of the deduced sequence of the human cardiac cGI-PDE. These and other results suggest that the subunit size of the intact platelet cGI-PDE is 110 kDa and that proteolytic fragments of 79, 62 and 55/53 kDa are produced during purification. The smaller fragments (62 and 55/53 kDa) contain the catalytic domain; the larger fragments (110 and 79 kDa) also contain the regulatory domain with phosphorylation sites for A-kinase.
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| 4. |
- Andersson, Britt M., et al.
(författare)
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Electrical resistivity and critical temperature of Bi-based high-Tc superconductors to 1 GPa
- 1990
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Ingår i: High Pressure Research, volumes 3 to 5. - London : Gordon and Breach. - 2881247466 ; 3:1-6, s. 120-122
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Konferensbidrag (refereegranskat)abstract
- We have measured the electrical resistance R of a sintered, two-phase, high-TC superconductor with the nominal composition BiSrCaCu2Ox, as a function of T and p. We find d(lnR)/dp ≃ -0.06 GPa-1 at 295 K, while dTC/dp is 2.5 K/GPa for the phase with Tc ≃ 76 and 2 K/GPa for that with TC ≃ 106 K.
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| 5. |
- Berg, Roger, et al.
(författare)
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Time-resolved tranillumination imaging
- 1993
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Ingår i: Medical Optical Tomography: Functional Imaging and Monitoring. ; , s. 397-424
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Bokkapitel (refereegranskat)
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