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Electrical Stimulation of Carotid Sinus in Conscious Normotensive and Spontaneously Hypertensive Rats
Author(s) -
Domingos Gean,
SantosAlmeida Fernanda,
Silva Luiz Eduardo,
Dias Daniel,
Silva Carlos Alberto,
Castania Jaci,
Salgado Helio,
Fazan Rubens
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.648.10
Subject(s) - stimulation , medicine , bradycardia , heart rate , blood pressure , carotid sinus , anesthesia , femoral artery , carotid arteries , common carotid artery , mean arterial pressure , endocrinology
Electrical stimulation (ES) of the carotid sinus (CS) has been used to treat resistant arterial hypertension. Our aim was to evaluate, in conscious normotensive and spontaneously hypertensive rats (SHR), the effect of sustained (60 min) ES of CS on arterial pressure (AP), heart rate (HR) and heart rate variability (HRV). Male Wistar rats (n=8) and SHR (n=8) had the left CS surrounded by a pair of electrodes and insulated from adjacent tissues. A catheter was introduced into the femoral artery and exteriorized together with the CS electrodes. On the next day, conscious rats under continuous recording of AP had their CS stimulated with square pulses of 1 mA, 1 ms, and 30 Hz, delivered randomly, continuously or intermittently (20/20 s ON/OFF), during 60 min. On the following day the type of CS stimulation was inverted. To analyze HRV, segments of 5 min were selected immediately before, at the onset, middle and end of ES period. Greater sustained fall in AP due to ES of CS was observed in SHR (‐50±7 vs ‐11±2 mmHg). A conspicuous bradycardia was also elicited by sustained ES of the CS (‐62±15 and ‐32±11 bpm in SHR and Wistar rats). No difference was observed between continuous or intermittent ES of CS. Overall, HRV was increased by ES of CS only in SHR (from 4.8±0.6 to 11.7±3.2, 7.0±0.6 and 6.7±1.0 bpm at the onset, middle and end of ES). Surprisingly, no differences were observed in HR spectra during ES of CS in both groups. We conclude that ES of the CS was more effective to reduce AP and HR in SHR as compared to normotensive rats. Moreover, despite a marked effect of ES in overall HRV in SHR, no changes in HR spectra were observed. Financial Support: FAPESP, CAPES and CNPq.