Neurocardiogenic adjustment to chronic hypertensive pregnancy

[M. Jovanović]

63 str.

Medicina - Fiziološke nauke / Medicine - Physiological sciences

Adaptacija kardiovaskularnog sistema (KVS) na trudnoću podrazumeva niz hemodinamskih promena izazvanih remodelovanjem perifernih i centralnih mehanizama. Pad krvnog pritiska (BP) u trudnoći aktivira barorefleks, koji povećava tonus simpatikusa ka KVS i sintezu i lučenje vazopresina (VP). Poznato je da VP ima ulogu u adaptaciji na normotenzivnu trudnoću, ali i u razvoju primarne hipertenzije. Ipak, uticaj VP-a na neuroendokrinu i autonomnu adaptaciju KVS tokom hronično hipertenzivne trudnoće nije dovoljno istražen. Ova studija je izvedena na ženkama normotenzivnih Wistar (WR) i spontano hipertenzivnih pacova (SHR) sa ugrađenim radiotelemetrijskim uređajem za kontinuirano hemodinamsko merenje. Spektralnom analizom je procenjena varijabilnost BP-a i srčane frekvencije (HR), a osetljivosti barorefleksa (BRS) primenom metode sekvence. Koncentracija VP-a u plazmi je određena ELISA testom, a ekspresija gena VP, V1aR i V1bR, RT-qPCR metodom. Rezultati našeg istraživanja pokazuju da negravidne SHR ženke imaju veću ekspresiju gena za VP, V1aR i V1bR u PVN-u i SON-u u odnosu na WR ženke u diestrusu. Gravidne SHR ženke imaju smanjenu ekspresiju VP-a u SON-u, niži VP u plazmi i normalan BP tokom kasne trudnoće, ali i znake pojačane simpatičke srčane stimulacije (porast HR i LF-HR), kao i angažovanje vagalnih mehanizama (uvećanje BRS-a i HF-HR). Kod WR ženki kasna trudnoća je podstakla povišenu ekspresiju gena za VP u PVN-u i SON-u, dok je pad nivoa VP-a u plazmi i BP-a manje izražen nego kod SHR-ova, a značajne promene parametara autonomne kontrole su izostale. Ovi rezultati ukazuju na postojanje razlika u neurokardiogenoj adaptaciji na trudnoću između ženki WR-a i SHR-ova.

Cardiovascular system (CVS) adjustment to pregnancy encompasses numerous hemodynamic changes induced by the remodeling of peripheral and central mechanisms. During pregnancy, arterial blood pressure drop activates the baroreflex, which increases sympathetic tone towards the CVS, and the synthesis and secretion of vasopressin (VP). It is known that VP is involved both in adaptation to normotensive pregnancy as well as in development of primary hypertension. Yet, the impact of VP to the neuroendocrine and autonomic adaptations of the CVS to chronic hypertensive pregnancy is not fully investigated. This study was performed on female normotensive Wistar (WRs) and Spontaneously hypertensive rats (SHRs), equipped with a radiotelemetry device for continuous hemodynamic recording. Variability of blood pressure (BP) and heart rate (HR) was estimated by spectral analysis, while baroreceptor reflex sensitivity (BRS) was evaluated using the sequence method. Plasma VP was determined by ELISA whereas VP, V1aR, and V1bR gene expression was detected by RT-qPCR. Our results show that non-pregnant SHRs exhibit greater VP, V1aR and V1bR gene expression in both PVN and SON compared to Wistar diestrus females. Pregnant SHR dams display reduced expression of VP in SON, lower plasma VP and normal BP during late pregnancy, as well as marked signs of enhanced sympathetic cardiac stimulation (increased HR and LF-HR variability) and recruitment of vagal mechanisms (enhanced BRS and HF-HR variability). In WR females, late pregnancy increased VP gene expression both in the PVN and SON, while the drop of plasma VP levels and BP were less pronounced compared to SHRs and no significant changes in autonomic control parameters were present. These results suggest a differential neurocardiogenic adaptation to pregnancy in WR and SHR females.

trudnoća, hronična hipertenzija, vazopresin, vazopresinski receptori, osetljivost barorefleksa, kardiovaskularni varijabilitet, paraventrikularno jedro, supraoptičko jedro

pregnancy, chronic hypertension, vasopressin, vasopressin receptors, baroreflex sensitivity, cardiovascular variability, paraventricular nucleus, supraoptic nucleus

616.12-008.331.1:618.2(043.3)

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