Distinct Role of Endothelial Caveolae in Contraction and Relaxation Responses of Aortas from Pregnant Normotensive and Hypertensive Rats

Abstract

We evaluated the role of endothelial caveolae in contraction and relaxation of aortas of Wistar and spontaneously hypertensive rats (SHR) at the end of pregnancy. The quantification of the endothelial caveolae number in the absence or presence of methyl‐β‐ciclodextrin (DEX,10 mM/L) in aortas from non‐pregnant (NP) and pregnant (P) Wistar and SHR with 12 weeks old (n= 5) was assessed by electronic microscopy. Aorta rings from different groups (n= 5) were stimulated with cumulative concentrations (1 nM/L to 10 μM/L) of phenylephrine (PE) or acetylcholine (Ach) in the absence or presence of DEX (10 mM/L). We performed the analysis of caveolin‐1 (cav‐1) and p‐cav‐1 expression by Western Blot in aortic homogenates (n= 5). Ethics committee FOA‐UNESP proc. 00730/2015. The results were compared among groups (ANOVA, p <0.05). Hypertensive NP rats present a reduced number of caveolae in aortas when compared to aortas from Wistar NP. Wistar P has a lower number of caveolae in aortas when compared to aortas from Wistar NP, but the number of caveolae was not altered between aortas of SHR P and SHR NP. DEX was able to reduce the number of caveolae in aortas only in the NP groups of normotensive or hypertensive rats. Vascular reactivity assays showed that in the presence of DEX the aortas of the Wistar NP and SHR NP groups had an increase in the contractile response to PE as well as a reduction in the potency of ACh. However, in aortas of the Wistar P and SHR P groups had no change in the contractile response for PE and ACh. p‐cav‐1/cav‐1 expression is decreased in aortas of SHR NP when compared to Wistar NP. Pregnancy does not alter p‐cav‐1/cav‐1 expression in aortas of Wistar rats, but it increases cav‐1 phosphorylation in SHR aortas. These results showed that pregnancy does not alter the reduced number of caveolae in aortas of hypertensive rats. Due to the reduced number of caveolae in aortas of pregnant rats, DEX would have no effect on aortic reactivity to PE or ACh. Although the reduced number of caveolae, the increased p‐cav‐1 expression in aortas of SHR P could be associated with increased eNOS activity and consequently lower NO‐dependent reactivity, from aortas to PE.Support or Funding InformationFAPESP 2015/09373‐0; 2016/22180‐9; 2018/10635‐7 and CAPES.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.