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Effects of substance P on nicotine-induced intracellular Ca2+ dynamics in bovine adrenal chromaffin cells
1999
Suzuki, S. (Hokkaido Univ., Sapporo (Japan)) | Habara, Y. | Kanno, T.
Substance P (SP) is colocalized with ACh in splanchnic nerves that innervate into adrenal medulla and the peptide has been shown to inhibit nicotinic agonists-induced catecholamine secretion. To elucidate the effects of SP on cytosolic Ca(2+) dynamics, the present study was conducted using fura-2-loaded isolated bovine adrenal chromaffin cells. Stimulation of the cells with nicotine (10-100mu-M) produced a rapid rise of cytosolic Ca(2+) concentration ([Ca(2+)]i), the peak level of which increased in a dose-dependent manner, followed by a gradual decay. In the presence of 10mu-M SP, the dose-response relationship of the peak levels shifted downward. Quantitative analyses implied that SP inhibits the nicotine-induced Ca(2+) influx in a noncompetitive manner. Nicotinic acetylcholine receptor is composed of two major functional domains: an agonist-binding site and an ionophore or channel domain. Agonist binding activates ionophore / channel domain and causes mainly Na(+) influx. This Na(+) influx depolarizes the cell and activates voltage-dependent Ca(2+) channels. Based on this fact, the present results indicate that SP dose not block nicotine binding sites but interferes with other sites of nicotinic receptor / channel molecule, most probably a channel domain. It was suggested that SP colocalized with ACh in splanchnic nerves functions as a physiological modulator of catecholamine secretion by non-competitively suppressing ACh-induced cytosolic Ca(2+) dynamics in bovine a
Show more [+] Less [-]Assessment of cattle owners' perceptions and expectations, and identification of constraints on production in a peri-urban, resource-poor environment
1999
Dreyer, K. | Fourie, L.J. | Kok, D.J. (Orange Free State Univ., Bloemfontein (South Africa). Dept. of Zoology and Entomology)
The parasitological and serological prevalence of tsetse-transmitted bovine trypanosomosis in the Eastern Caprivi (Caprivi District, Namibia)
1999
Van den Bossche, P. | Mudenge, D. (Regional Tsetse and Trypanosomosis Control Programme, Harare (Zimbabwe)) | Mubanga, J. | Norval, A.
Comparison of indirect fluorescent antibody test and enzyme linked immunosorbent assay in the detection of exposure of cattle to Theileria parva in Kenya
1999
Muraguri, G.R. | Gitau, P.K. | Mwangi, M.N. | Mbogo, S.K. | Kariuki, D.P. (Kenya Agricultural Research Inst., Kikuyu (Kenya). National Veterinary Research Centre)
A serological survey of bovine babesiosis in northern and eastern Zimbabwe
1999
Katsande, T.C. (Central Veterinary Laboratory, Harare (Zimbabwe)) | More, S.J. | Bock, R.E. | Mabikacheche, L. | Molloy, J.B. | Ncube, C.
Gastro-intestinal parasites of cattle in the communal grazing system of Botshabelo in the Free State [South Africa]
1999
Dreyer, K. | Fourie, L.J. | Kok, D.J. (Orange Free State Univ., Bloemfontein (South Africa). Dept. of Zoology and Entomology)