Refinar búsqueda
Resultados 1-5 de 5
Effects of tumor necrosis factor on in vitro digital arterial responses in horses
1994
Baxter, G.
Endotoxin given in vivo has been shown to inhibit endothelial dependent relaxation, and augment adrenergic (norepinephrine) contractions in isolated palmar digital arteries of horses. A study, using tumor necrosis factor (TNF) in vitro, was performed to determine the possible cause of these vascular alterations. Palmar digital arteries were surgically removed from 6 horses under general anesthesia, cut into 4-mm vascular rings (4 segments/horse), suspended in tissue baths, and attached to force displacement transducers for measurement of vascular tension. Four in vitro treatment groups were evaluated: group 1, control; group 2, TNF (5,100 pg of TNF/ml); group 3, 10x TNF (10 times previous TNF concentration); group 4, TNF plus L-arginine (5,100 pg of TNF/ml and 10(-6) M L-arginine). The appropriate drug(s) was/were added to each tissue bath 10 minutes before dose-response tests were performed for acetylcholine, bradykinin, norepinephrine, and 5-hydroxytryptamine (serotonin). Concentrations needed to induce 50% maximal relaxation or contraction (EC50) and maximal percentage relaxation or contraction were determined. Arteries exposed to TNF (group 2) had significantly (P = 0.04) decreased maximal relaxation to acetylcholine and increased maximal contraction to norepinephrine, compared with control arteries, but values did not differ from those for arteries of groups 3 and 4. Maximal relaxation to bradykinin or contraction to serotonin were not different between treatment groups. Mean EC50 values for bradykinin, norepinephrine, and serotonin did not differ among the 4 treatment groups. Mean EC50 values for arterial segments' response to acetylcholine in group 4 were significantly (P = 0.04) increased, compared with control segments, but did not differ from those for segments of groups 2 and 3. The decreased endothelial dependent relaxation to acetylcholine and enhanced maximal contraction to norepinephrine were similar to vascular alterations caused by endotoxin, indicating that TNF may be responsible for endotoxin-induced vascular changes in vitro and in vivo in horses.
Mostrar más [+] Menos [-]The inhibitory action of lead on mechanical responses of the proventricular smooth muscle in the chick
1994
Kubota, K. (Hokkaido Univ., Sapporo (Japan). Faculty of Veterinary Medicine) | Ito, S. | Ohta, T. | Nakazato, Y. | Ohga, A.
Characterization of the drug receptors responsible for intestinal contraction in Israeli carp
1994
Yun, H.I. | Han, K.O. | Park, S.C. (Chungnam National University, Taejon (Korea Republic). College of Veterinary Medicine) | Cho, J.H. (Rural Development Administration, Anyang (Korea Republic). Veterinary Research Institute) | Oh, T.K. (Korea Advanced Institute of Science and Technology, Taejon (Korea Republic). Genetic Engineering Research Institute)
Actions of acetylcholine, norepinephrine, histamine and prostaglandin F2alpha on motility of pig oviductal isthmic smooth muscle
1994
Rho, G.J. | Kim, J.H. | Choe, S.Y. (Gyeongsang National University, Chinju (Korea Republic). College of Veterinary Medicine) | Park, S.E. (Gyeongnam Veterinary Medicine, Masan (Korea Republic). Central Branch) | Shim, C.S. (Gyeongnam Veterinary Medicine, Yangsan (Korea Republic). Eastern Branch)
Effect of calcitonin gene-related peptide, vasoactive intestinal peptide and substance P on isolated renal artery of rabbit
1994
Kim, J.H. (Gyeongsang National University, Chinju (Korea Republic). College of Veterinary Medicine) | Shim, C.S. (Gyeongnam Animal Health Institute, Yangsan (Korea Republic). Eastern Branch) | Park, S.E. (Gyeongnam Animal Health Institute, Masan (Korea Republic). Central Branch)