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First published online December 22, 2003
Journal of Experimental Biology 207, 411-416 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00778

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Stimulation of the -adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca

Celine M. Kerchove¹, Sylvia M. Carneiro², Regina P. Markus³ and Norma Yamanouye^1,*

¹ Laboratório de Farmacologia, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900, São Paulo, Brazil
² Laboratório de Biologia Celular, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900, São Paulo, Brazil
³ Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, travessa 14, 05508-900 São Paulo, Brazil

View larger version (14K): [in a new window]   Fig. 1. Dose–response curves for noradrenaline (open squares, N=7) and phenylephrine (filled squares, N=11) in quiescent cells of the venom gland of Bothrops jararaca, as assessed by microphysiometry. Cultured cells were perfused with the agonists for 1 min, a complete dose–reponse curve was constructed in each well, and the interval between successive doses was 30 min. All experiments were done in the presence of the ß-adrenoceptor blocker propranolol. Values are means ± S.E.M.

View larger version (19K): [in a new window]   Fig. 2. Dose–response curves to phenylephrine in secretory cells in different stages of the venom production cycle: quiescent cells (filled squares, N=11), cells collected just after venom extraction (open triangles, N=6), cells collected 4 days (open circles, N=6), 7 days (open diamonds, N=5), 15 days (asterisks, N=6) and 30 days after venom extraction (filled circles, N=6). Note that venom extraction induced receptor downregulation that lasted for at least 15 days. Values are means ± S.E.M.

View larger version (16K): [in a new window]   Fig. 3. In vitro desensitization of the -adrenoceptor in cells of the Bothrops jararaca venom gland. Quiescent cells were incubated for 5 min with 10–4 mol l–1 noradrenaline and kept at 30°C for 24 h(triangles, N=6) before the construction of the dose–response curve to phenylephrine. Control quiescent cells (squares, N=11). Note that incubation with noradrenaline induced receptor downregulation. Values are means ± S.E.M.

View larger version (179K): [in a new window]   Fig. 4. Effect of a single dose of phenylephrine (100 mg kg–1 wet mass, s.c., N=3) on morphology of venom gland cells of reserpine-treated snakes. (A) Venom gland obtained from venom-extracted snakes after treatment with reserpine for 15 days. (B) Venom gland obtained from venom-extracted snakes after treatment with reserpine plus phenylephrine immediately after venom extraction. Note in A the narrow cisterna of the rough endoplasmatic reticulum indicative of lack of venom synthesis and a quiescent Golgi and in B the presence of wide rough endoplasmatic reticulum cisternae and several vesicles in the Golgi complex suggestive of venom production and secretion. G, Golgi apparatus; L, lumen; R, rough endoplasmic reticulum; S, secretory vesicle. Scale bars, 2 µm.