RESUMEN
A autora aborda a clínica do sintoma nos sujeitos femininos. Apresenta duas vinhetas clínicas para demonstrar, com o sujeito não separado de seu objeto oral e com uma compradora aditiva, como o sintoma se associa ao parceiro da fantasia na vida amorosa, e também como ele se apóia no corpo do sujeito e nos objetos do Outro. Em cada um dos casos o sintoma se apresenta com uma consistência enigmática, dolorosa e culpada, abastecendo-se de uma conotação maciça do "é mais forte do que eu
RESUMEN
Xestospongin B, a macrocyclic bis-1-oxaquinolizidine alkaloid extracted from the marine sponge Xestospongia exigua, was highly purified and tested for its ability to block inositol 1,4,5-trisphosphate (IP(3))-induced Ca(2+) release. In a concentration-dependent manner xestospongin B displaced [(3)H]IP(3) from both rat cerebellar membranes and rat skeletal myotube homogenates with an EC(50) of 44.6 +/- 1.1 microM and 27.4 +/- 1.1 microM, respectively. Xestospongin B, depending on the dose, suppressed bradykinin-induced Ca(2+) signals in neuroblastoma (NG108-15) cells, and also selectively blocked the slow intracellular Ca(2+) signal induced by membrane depolarization with high external K(+) (47 mM) in rat skeletal myotubes. This slow Ca(2+) signal is unrelated to muscle contraction, and involves IP(3) receptors. In highly purified isolated nuclei from rat skeletal myotubes, Xestospongin B reduced, or suppressed IP(3)-induced Ca(2+) oscillations with an EC(50) = 18.9 +/- 1.35 microM. In rat myotubes exposed to a Ca(2+)-free medium, Xestospongin B neither depleted sarcoplasmic reticulum Ca(2+) stores, nor modified thapsigargin action and did not affect capacitative Ca(2+) entry after thapsigargin-induced depletion of Ca(2+) stores. Ca(2+)-ATPase activity measured in skeletal myotube homogenates remained unaffected by Xestospongin B. It is concluded that xestospongin B is an effective cell-permeant, competitive inhibitor of IP(3) receptors in cultured rat myotubes, isolated myonuclei, and neuroblastoma (NG108-15) cells.
Asunto(s)
Alcaloides/farmacología , Señalización del Calcio/efectos de los fármacos , Inositol 1,4,5-Trifosfato/farmacología , Fibras Musculares Esqueléticas/efectos de los fármacos , Neuroblastoma/metabolismo , Animales , Unión Competitiva , Línea Celular Tumoral , Células Cultivadas , Compuestos Macrocíclicos , Ratones , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patología , Neuroblastoma/patología , Oxazoles , RatasRESUMEN
Homenaje a Jacques Lacan en el centenario de su nacimiento