title: Baroreflex regulation affects ventilation in the cururu toad Rhinella schneideri.
abstract: Anurans regulate short-term oscillations in blood pressure through changes in heart rate (fH), vascular resistance and lymphatic fHLung ventilation in anurans is linked to blood volume homeostasis by facilitating lymph return to the cardiovascular system. We hypothesized that the arterial baroreflex modulates pulmonary ventilation in the cururu toad Rhinella schneideri, and that this relationship is temperature dependent. Pharmacologically induced hypotension (sodium nitroprusside) and hypertension (phenylephrine) increased ventilation (25°C: 248.7±25.7 ml kg-1min-1; 35°C: 351.5±50.2 ml kg-1min-1) and decreased ventilation (25°C: 9.0±6.6 ml kg-1min-1; 35°C: 50.7±15.6 ml kg-1min-1), respectively, relative to control values from Ringer solution injection (25°C: 78.1±17.0 ml kg-1min-1; 35°C: 137.7±15.5 ml kg-1min-1). The sensitivity of the ventilatory response to blood pressure changes was higher during hypotension than during hypertension [25°C: -97.6±17.1 versus -23.6±6.0 breaths min-1kPa-1; 35°C: -141.0±29.5 versus -28.7±6.4 breaths min-1kPa-1, respectively; negative values indicate an inverse relationship between blood pressure and ventilation (or breathing frequency), i.e. as blood pressure increases, ventilation decreases, and vice versa], while temperature had no effect on these sensitivities. Hyperoxia (30%; 25°C) diminished ventilation, but did not abolish the ventilatory response to hypotension, indicating a response independent of peripheral chemoreceptors. Although there are previous data showing increased fHbaroreflex sensitivity from 15 to 30°C in this species, further increases in temperature (35°C) diminished fHbaroreflex gain (40.5±5.62 versus 21.6±4.64% kPa-1). Therefore, besides an involvement of pulmonary ventilation in matching O2delivery to demand at higher temperatures in anurans, it also plays a role in blood pressure regulation, independent of temperature, possibly owing to an interaction between baroreflex and respiratory areas in the brain, as previously suggested for mammals.
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil lucaszena@yahoo.com.br keniacb@fcav.unesp.br.|National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Jaboticabal, São Paulo 14884-900, Brazil.
authors.forename: Lucas A
authors.identifier: 0000-0002-4422-4458
authors.initials: LA
authors.lastname: Zena
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil.|National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Jaboticabal, São Paulo 14884-900, Brazil.
authors.forename: Glauber S F
authors.initials: GS
authors.lastname: da Silva
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil.|National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Jaboticabal, São Paulo 14884-900, Brazil.
authors.forename: Luciane H
authors.initials: LH
authors.lastname: Gargaglioni
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo 14884-900, Brazil lucaszena@yahoo.com.br keniacb@fcav.unesp.br.|National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Jaboticabal, São Paulo 14884-900, Brazil.
authors.forename: Kênia C
authors.initials: KC
authors.lastname: Bícego
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D001285:Atropine / Q000494:pharmacology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D018496:Hyperoxia / Q000150:complications / Q000503:physiopathology; D007022:Hypotension / Q000139:chemically induced / Q000150:complications / Q000503:physiopathology; D009599:Nitroprusside; D012123:Pulmonary Ventilation / Q000187:drug effects / Q000502:physiology*; D011941:Receptors, Adrenergic / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism; D012044:Regression Analysis; D012119:Respiration / Q000187:drug effects; D013015:Sotalol / Q000494:pharmacology; D013696:Temperature
chemical_list: D011941:Receptors, Adrenergic; D011950:Receptors, Cholinergic; D009599:Nitroprusside; D001285:Atropine; D013015:Sotalol
keywords: Anuran amphibians; Autonomic blockade; Baroreceptors; Chemoreceptors; Hyperoxia; Lung ventilation