Subject(s)
Enterocolitis/veterinary , Horse Diseases/diagnosis , Hypereosinophilic Syndrome/veterinary , Intestinal Obstruction/veterinary , Pregnancy Complications/veterinary , Animals , Diarrhea/veterinary , Enterocolitis/etiology , Enterocolitis/surgery , Fatal Outcome , Female , Horse Diseases/etiology , Horse Diseases/surgery , Horses , Hypereosinophilic Syndrome/complications , Hypereosinophilic Syndrome/diagnosis , Intestinal Obstruction/etiology , Intestinal Obstruction/surgery , Pregnancy , Pregnancy Complications/etiology , Pregnancy Complications/surgery , Recurrence , Weight LossSubject(s)
Horse Diseases/etiology , Lameness, Animal/etiology , Panniculitis, Nodular Nonsuppurative/veterinary , Animals , Biopsy, Needle/veterinary , Female , Horse Diseases/pathology , Horses , Panniculitis, Nodular Nonsuppurative/complications , Panniculitis, Nodular Nonsuppurative/pathology , Recurrence , StifleABSTRACT
The cytoskeleton and/or membrane skeleton has been implicated in the regulation of N-formyl peptide receptors. The coupling of these chemotactic receptors to the membrane skeleton was investigated in plasma membranes from unstimulated and desensitized human neutrophils using the photoreactive agonist N-formyl-met-leu-phe-lys-N epsilon-[125I]2(p-azidosalicylamido)ethyl-1,3'- dithiopropionate (fMLFK-[125I]ASD). When membranes of unstimulated cells were solubilized in Triton-X 100, a detergent that does not disrupt actin filaments, only 50% of the photoaffinity-labeled receptors were solubilized sedimenting in sucrose density gradients at a rate consistent with previous reports. The remainder were found in the pellet fraction along with the membrane skeletal actin. Solubilization of the membranes in the presence of p-chloromercuriphenylsulfonic acid, elevated concentrations of KCl, or deoxyribonuclease I released receptors in parallel with actin. When membranes from neutrophils, desensitized by incubation with fMLFK-[125I]ASD at 15 degrees C, were solubilized, nearly all receptors were recovered in the pellet fraction. Incubation of cells with the ligand at 4 degrees C inhibited desensitization partially and prevented the conversion of a significant fraction of receptors to the form associated with the membrane skeletal pellet. In these separations the photoaffinity-labeled receptors not sedimenting to the pellet cosedimented with actin. Approximately 25% of these receptors could be immunosedimented with antiactin antibodies suggesting that N-formyl peptide receptors may interact directly with actin. These results are consistent with a regulatory role for the interaction of chemotactic N-formyl peptide receptors with actin of the membrane skeleton.