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Salman IM, Ameer OZ, McMurray S, Giarola AS, Sridhar A, Lewis SJ, Hsieh YH. Laterality Influences Central Integration of Baroreceptor Afferent Input in Male and Female Sprague Dawley Rats. Front Physiol 2020; 11:499. [PMID: 32536876 PMCID: PMC7269127 DOI: 10.3389/fphys.2020.00499] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/23/2020] [Indexed: 12/02/2022] Open
Abstract
We explored the effects of baroreceptor afferents laterality and sexual dimorphism on the expression of cardiovascular reflex responses to baroreflex activation in Sprague Dawley (SD) rats. Under urethane anesthesia, rats of either sex (total n = 18) were instrumented for left, right and bilateral aortic depressor nerve (ADN) stimulation (1–40 Hz, 0.2 ms, 0.4 mA for 20 s) and measurement of mean arterial pressure (MAP), heart rate (HR) and mesenteric (MVR) and femoral (FVR) vascular resistance. Female rats were matched for the diestrus phase of the estrus cycle. Left, right and bilateral ADN stimulation evoked frequency-dependent drops in MAP, HR, and MVR, and increases in FVR. Irrespective of sex, left and bilateral ADN stimulation as compared to right-sided stimulation mediated greater reflex reductions in MAP, HR, and MVR but not in FVR. In males, reflex bradycardic responses were greater in response to bilateral stimulation relative to both left- and right-sided stimulation. In females, left ADN stimulation evoked the largest increase in FVR. Left and bilateral ADN stimulations evoked greater reductions in MAP and MVR while left-sided stimulation produced larger increases in FVR in females compared with males. All other reflex responses to ADN stimulation were relatively comparable between males and females. These results show a differential baroreflex processing of afferent neurotransmission promoted by left versus right baroreceptor afferent inputs and sexual dimorphism in the expression of baroreflex responses in rats of either sex. Collectively, these data add to our understanding of physiological mechanisms pertaining to baroreflex control in both males and females.
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Affiliation(s)
- Ibrahim M Salman
- College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia.,Division of Pulmonology, Allergy and Immunology, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Omar Z Ameer
- College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia
| | - Sheridan McMurray
- Department of Disease Biology, Galvani Bioelectronics, Hertfordshire, United Kingdom
| | - Alessandra S Giarola
- Department of Disease Biology, Galvani Bioelectronics, Hertfordshire, United Kingdom
| | - Arun Sridhar
- Department of Disease Biology, Galvani Bioelectronics, Hertfordshire, United Kingdom
| | - Stephen J Lewis
- Division of Pulmonology, Allergy and Immunology, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Yee-Hsee Hsieh
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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Tohyama T, Hosokawa K, Saku K, Oga Y, Tsutsui H, Sunagawa K. Smart Baroreceptor Activation Therapy Strikingly Attenuates Blood Pressure Variability in Hypertensive Rats With Impaired Baroreceptor. Hypertension 2020; 75:885-892. [DOI: 10.1161/hypertensionaha.119.13673] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Increased blood pressure (BP) variability (BPV) is an independent risk factor of cardiovascular events among hypertensive patients. The arterial baroreceptor reflex is a powerful regulator of BP and attenuates BPV via a sympathetic negative feedback control. Conventional baroreceptor activation therapy (cBAT) electrically stimulates the carotid baroreceptors with constant stimulation parameters. While cBAT lowers BP, it does not mount a pressure feedback mechanism. We hypothesized that baroreceptor activation therapy with a pressure feedback system (smart BAT [sBAT]) is able to reduce BPV as well as lower BP. We developed sBAT that electrically stimulated baroreceptors at a frequency proportional to the difference between instantaneous BP and a preset reference pressure, and compared its performance with cBAT. In 14-week-old spontaneously hypertensive rats (n=6), we implanted BP telemeter and created impaired arterial baroreceptors by modified sino-aortic denervation. One week after surgical preparation, we administered sBAT, cBAT or no stimulation (sham) for 15 minutes and compared BP and BPV under freely moving condition. Both cBAT and sBAT significantly lowered mean BP (sham, 141.3±12.8; cBAT, 114.3±11.4; and sBAT, 112.0±7.3 mm Hg). Conventional BAT did not affect BPV at all, while sBAT significantly reduced BPV (sham, 15.4±2.6; cBAT, 16.0±5.2; and sBAT, 9.7±3.3 mm Hg). sBAT also prevented transient excessive BP rise and fall. In conclusion, sBAT was capable of reducing BP and attenuating BPV in hypertensive rats with impaired baroreceptor. sBAT is a novel treatment option for hypertensive patients with increased BPV.
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Affiliation(s)
- Takeshi Tohyama
- From the Department of Cardiovascular Medicine, Graduate School of Medical Sciences (T.T., K. Saku, Y.O., H.T.), Kyushu University, Fukuoka, Japan
| | - Kazuya Hosokawa
- Department of Cardiovascular Medicine, Kyushu University Hospital, Fukuoka, Japan (K.H., H.T.)
| | - Keita Saku
- From the Department of Cardiovascular Medicine, Graduate School of Medical Sciences (T.T., K. Saku, Y.O., H.T.), Kyushu University, Fukuoka, Japan
| | - Yasuhiro Oga
- From the Department of Cardiovascular Medicine, Graduate School of Medical Sciences (T.T., K. Saku, Y.O., H.T.), Kyushu University, Fukuoka, Japan
| | - Hiroyuki Tsutsui
- From the Department of Cardiovascular Medicine, Graduate School of Medical Sciences (T.T., K. Saku, Y.O., H.T.), Kyushu University, Fukuoka, Japan
- Department of Cardiovascular Medicine, Kyushu University Hospital, Fukuoka, Japan (K.H., H.T.)
| | - Kenji Sunagawa
- Department of Therapeutic Regulation of Cardiovascular Homeostasis, Center for Disruptive Cardiovascular Medicine (K. Sunagawa), Kyushu University, Fukuoka, Japan
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