FPL-64176

Several 4H-pyran derivatives were designed and synthesized previously as vasorelaxant agents for potential antihypertensive drugs. In this context, the objective of the present investigation was to determine the functional mechanism of vasorelaxant action of 6-amino-3-methyl-4-(2-nitrophenyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (1) and its in vivo antihypertensive effect. Thus, compound 1 showed significant vasorelaxant action on isolated aorta rat rings pre-contracted with serotonin or noradrenaline, and the effect was not endothelium-dependent. Compound 1 induced a significant relaxant effect when aortic rings were contracted with KCl (80 mM), indicating that the main mechanism of action is related to L-type calcium channel blockade. Last was corroborated since compound 1 induced a significant concentration-dependent lowering of contraction provoked by cumulative CaCl2 adding. Moreover, compound 1 was capable to block the contraction induced by FPL 64176, a specific L-type calcium channel agonist, in a concentration-dependent manner. On the other hand, docking studies revealed that compound 1 interacts on two possible sites of the L-type calcium channel and it had better affinity energy (−7.80+/−0.00 kcal/mol on the best poses) than nifedipine (−6.86+/−0.14 kcal/mol). Finally, compound 1 (50 mg/kg) showed significant antihypertensive activity, lowering the systolic and diastolic blood pressure on spontaneously hypertensive rats (SHR) without modifying heart rate.

Increasing evidence has shown that voltage-gated L-type Ca²⁺ channels (LTCCs) are crucial for neurodevelopmental events, including neuronal differentiation/migration and neurite morphogenesis/extension. However, the time course of their functional maturation during the development of excitatory neurons remains unknown. Using a combination of fluorescence in situ hybridization and in utero electroporation-based labeling, we found that the transcripts of Cacna1c and Cacna1d, which encode the LTCC pore-forming subunits, were upregulated in the intermediate zone (IZ) during radial migration. Ca²⁺ imaging using GCaMP6s in acute brain slices showed spontaneous Ca²⁺ transients in migrating neurons throughout the IZ. Neurons in the IZ upper layer, especially in the multipolar-to-bipolar transition layer (TL), exhibited more frequent Ca²⁺ transients than adjacent layers and responded to FPL64176, a potent activator of LTCC. Consistently, nimodipine, an LTCC blocker, inhibited spontaneous Ca²⁺ transients in neurons in the TL. Collectively, we showed a hitherto unknown increased prevalence of LTCC-dependent Ca²⁺ transients in the TL of the IZ upper layer during the radial migration of excitatory neurons, which could be essential for the regulation of Ca²⁺-dependent neurodevelopmental processes.