RESUMO
We have developed an endoscopic instrument that will allow a surgeon to safely, dependably and accurately place intramuscular (IM) electrodes in the diaphragm. This instrument has been used to implant 28 IM electrodes in the diaphragms of eleven acute and four chronic dogs. All electrodes achieved full activation of the diaphragm muscle, producing tidal volumes up to 130% V(TCRIT), the critical volume necessary for basal ventilatory support, with unilateral stimulation. The surgeon is able to control the angle of the IM electrode insertion needle, which enables the needle to approach the diaphragm at an angle that is parallel to the surface of the muscle. This insures good control over the depth of needle penetration into the muscle, which greatly reduces the risk of accidentally passing the needle through the diaphragm and entering the thorax. Endoscopic placement of IM electrodes into the diaphragm opens opportunities to provide cost effective negative pressure ventilation to patients who are unable to effect sufficient ventilation by central nervous system (CNS) control of respiration.
Assuntos
Diafragma/fisiologia , Diafragma/cirurgia , Eletrodos Implantados , Laparoscópios , Animais , Cães , Eletrocardiografia , Endoscopia , Desenho de Equipamento , Implantes Experimentais , Laparoscopia/métodos , Monitorização Fisiológica , Agulhas , Volume de Ventilação PulmonarRESUMO
Endothelin (ET) receptors display subtype heterogeneity and so far three subtypes of ET receptors, namely ETA, ETB, and ETC, have been identified, cloned, sequenced, and characterized. Based on the binding profile of ET and related peptides, a novel ET receptor (ETAX) was identified in the follicular membranes of Xenopus laevis oocytes (Kumar, C. S., Nuthulaganti, P., Pullen, M., and Nambi, P. (1993). Mol. Pharmacol. 44, 153-157). Here we report the cloning and characterization of this ETAX subtype from X. laevis heart. A cDNA was isolated that encodes a protein of 415 amino acids that shares 74, 60, and 51% identities with human ETA, human ETB, and Xenopus ETC receptors, respectively. Competition binding studies of the cloned receptor expressed in COS cells using ET-related peptides suggested that this receptor is pharmacologically identical to that expressed in Xenopus oocyte follicular, heart, and lung membranes. Phosphoinositide turnover and oocyte electrophysiological studies indicated that the cloned receptor is functionally coupled to a second messenger system.
