Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil. Electronic address: https://twitter.com/b07855682.
Department of Physiology, University of São Paulo (USP), Rua do Matão - Travessa 14 - N. 101, Cidade Universitária, São Paulo, SP 05508-090, Brazil.
Comp Biochem Physiol A Mol Integr Physiol. 2024 Feb;288:111554. doi: 10.1016/j.cbpa.2023.111554. Epub 2023 Nov 20.
Arterial pressure (Pa) regulation is essential to adequately distribute nutrients to metabolizing tissues, remove wastes and avoid lesions associated with hypertension. In vertebrates, short-term Pa regulation is achieved through the baroreflex, which elicits inversely proportional changes in heart rate (f) and vascular resistance to restore Pa. The cardiac limb of this reflex has been reported in all vertebrate groups studied to date: teleosts, amphibians, snakes, lizards, crocodiles, birds and mammals - which led to the suggestion that the baroreflex is an ancient trait present in all vertebrate species. However, it is not clear whether more basal groups of vertebrates, such as cyclostomes, elasmobranchs and chondrosteans, manifest baroreflex regulation of f. Thus, the aim of this study was to determine whether the white sturgeon (Acipenser transmontanus; Chondrostei: Acipenseridae) exhibits a cardiac baroreflex. To do so, we induced Pa perturbations through injections of phenylephrine, sodium nitroprusside (SNP) and saline solution (hypervolemia), and examined possible f baroreflex responses. We also investigated whether f responses triggered by fright and chemoreflex were present in this species, in order to confirm the potential of sturgeon to perform reflexive cardiac adjustments. The findings indicate that A. transmontanus exhibits reflex bradycardia in response to fright and chemoreceptor stimulation, illustrating its capacity for short-term cardiac regulation. However, this species does not display baroreflex control of f across its physiological range. This dissociation suggests that while the nervous and cardiovascular systems of A. transmontanus are primed for rapid reflex responses, a cardiac baroreflex mechanism remains absent.
动脉血压（Pa）调节对于向代谢组织充分分配营养物质、清除废物以及避免与高血压相关的损伤至关重要。在脊椎动物中，通过压力反射来实现短期的 Pa 调节，该反射会引起心率（f）和血管阻力的反向变化，以恢复 Pa。迄今为止，在所有研究过的脊椎动物群体中都报道了这种反射的心脏分支：硬骨鱼、两栖动物、蛇、蜥蜴、鳄鱼、鸟类和哺乳动物 - 这表明压力反射是一种存在于所有脊椎动物物种中的古老特征。然而，目前尚不清楚是否更基础的脊椎动物群体，如圆口类、软骨鱼类和硬骨鱼类，表现出 f 的压力反射调节。因此，本研究的目的是确定白鲟（Acipenser transmontanus；软骨鱼纲：鲟科）是否表现出心脏压力反射调节。为此，我们通过注射苯肾上腺素、硝普钠（SNP）和生理盐水（血容量过多）来诱导 Pa 波动，并检查可能的 f 压力反射反应。我们还研究了该物种是否存在因惊吓和化学感受器刺激引起的 f 反应，以确认鲟鱼进行反射性心脏调节的潜力。研究结果表明，A. transmontanus 在受到惊吓和化学感受器刺激时表现出反射性心动过缓，表明其具有短期心脏调节的能力。然而，该物种在其生理范围内不显示 f 的压力反射控制。这种分离表明，尽管 A. transmontanus 的神经系统和心血管系统已经为快速反射反应做好了准备，但心脏压力反射机制仍然缺失。
