Projects per year
Background and Purpose: Coordinated endothelial control of cardiovascular function is proposed to occur by endothelial cell communication via gap junctions and connexins. To study intercellular communication, the pharmacological agents carbenoxolone (CBX) and 18β-glycyrrhetinic acid (18βGA) are used widely as connexin inhibitors and gap junction blockers. Experimental Approach: We investigated the effects of CBX and 18βGA on intercellular Ca 2+ waves, evoked by inositol 1,4,5-trisphosphate (IP 3) in the endothelium of intact mesenteric resistance arteries. Key Results: Acetycholine-evoked IP 3-mediated Ca 2+ release and propagated waves were inhibited by CBX (100 μM) and 18βGA (40 μM). Unexpectedly, the Ca 2+ signals were inhibited uniformly in all cells, suggesting that CBX and 18βGA reduced Ca 2+ release. Localised photolysis of caged IP 3 (cIP 3) was used to provide precise spatiotemporal control of site of cell activation. Local cIP 3 photolysis generated reproducible Ca 2+ increases and Ca 2+ waves that propagated across cells distant to the photolysis site. CBX and 18βGA each blocked Ca 2+ waves in a time-dependent manner by inhibiting the initiating IP 3-evoked Ca 2+ release event rather than block of gap junctions. This effect was reversed on drug washout and was unaffected by small or intermediate K +-channel blockers. Furthermore, CBX and 18βGA each rapidly and reversibly collapsed the mitochondrial membrane potential. Conclusion and Implications: CBX and 18βGA inhibit IP 3-mediated Ca 2+ release and depolarise the mitochondrial membrane potential. These results suggest that CBX and 18βGA may block cell–cell communication by acting at sites that are unrelated to gap junctions.
- gap junctions
- inositol 1,4,5‐trisphosphate (IP3)
- carbenoxolone and 18β-glycyrrhetinic acid
17/04/17 → 16/10/21
Project: Research Fellowship