The interaction of cardiac Na+-Ca2+ exchange (NCX1) with caveolin proteins was investigated in sarcolemmal vesicles. Western blots of sarcolemmal vesicles revealed the presence of caveolin-1, -2, and -3. NCX1 co-fractionated more closely with caveolin-3 than caveolin-1 on sucrose density gradients. NCX1 has five possible caveolin-binding motifs and NCX1 co-precipitated specifically with caveolin-3. Molecular sieve column chromatography indicated that this co-precipitation was not due to incomplete solubilization of lipid raft microdomains. Cholesterol chelation in vesicles decreased NCX1 transport activity and caveolin-3 co-precipitation. NCX1 may play a role in caveolar transmembrane signaling in addition to its role in excitation-contraction coupling.

The purposes of this study were to describe cases of feline gastric lymphoma with regards to signalment, clinical presentation, laboratory and ancillary study findings, response to therapy, and outcomes and to identify prognostic variables. Sixteen cats with stage I and II gastric lymphoma treated with chemotherapy were included in this study. Seventy-five percent of cats experienced remission. Overall, first remission duration was 108 days. Response to treatment was prognostic as in other types of feline lymphoma. Cats with a complete remission (CR) had longer survival times compared with cats with a partial remission (PR). Sex and treatment with a rescue protocol were found to be prognostic with castrated males having longer survivals than spayed females. Cats that received rescue chemotherapy had shorter first remission durations than those that did not. Prior treatment with steroids and stage were not found to be significant prognostic variables. This study characterizes gastric lymphoma treated with chemotherapy in cats. Further studies are needed to determine the comparative efficacy of surgical and chemotherapeutic treatments for feline gastric lymphoma.

The cardiac Na/Ca exchanger's (NCX1) role in calcium homeostasis during myocardial contractility makes it a possible target of signaling factors regulating inotropy. Caveolae, structured invaginations of the plasmalemma, are known to concentrate a wide variety of signaling factors. The predominant coat proteins of caveolae, caveolins, dock to and regulate the activity of these signaling factors and other proteins through interaction with their scaffolding domain. In this study we investigated the interaction of NCX1 with caveolin proteins. Western blots of bovine cardiac sarcolemmal vesicles revealed the presence of caveolin‐1, ‐2, and ‐3. Immunoprecipitation of detergent‐solubilized vesicle proteins with either NCX1 or caveolin‐3 antibodies indicated that NCX1 coprecipitates with caveolin‐3, but not with caveolin‐1 and ‐2. Functional disruption of caveolae, by β‐cyclodextrin treatment of vesicles, diminished coprecipitation of caveolin‐3 and NCX1 activity. NCX1 has five potential caveolin‐binding motifs, two of which are in the transporter's exchange inhibitory peptide (XIP) domain. The presence of 50 mM XIP peptide enhanced coprecipitation of caveolin‐3 with NCX1 independent of calcium concentration. We conclude that NCX1 associates specifically with caveolin‐3. Partitioning of NCX1 in caveolae has implications for temporal and spatial regulation of excitation‐contraction and ‐relaxation coupling in cardiac myocytes.

This study demonstrates that cell block cytology is a practical and useful method for bone marrow evaluation and is suitable for cytokeratin immunocytochemical analysis.