Ionotropic but not metabotropic glutamatergic receptors in the locus coeruleus modulate the hypercapnic ventilatory response in unanaesthetized rats

Aim: Central chemoreceptors are important to detect changes of CO2/H+, and the Locus coeruleus (LC) is one of the many putative central chemoreceptor sites. Here, we studied the contribution of LC glutamatergic receptors on ventilatory, cardiovascular and thermal responses to hypercapnia. Methods: To this end, we determined pulmonary ventilation (VE), body temperatures (Tb), mean arterial pressure (MAP) and heart rate (HR) of male Wistar rats before and after unilateral microinjection of kynurenic acid (KY, an ionotropic glutamate receptor antagonist, 10 nmol/0.1 μL) or α-methyl-4-carboxyphenylglycine (MCPG, a metabotropic glutamate receptor antagonist, 10 nmol/0.1 μL) into the LC, followed by 60 min of air breathing or hypercapnia exposure (7% CO2). Results: Ventilatory response to hypercapnia was higher in animals treated with KY intra-LC (1918.7 ± 275.4) compared with the control group (1057.8 ± 213.9, P < 0.01). However, the MCPG treatment within the LC had no effect on the hypercapnia-induced hyperpnea. The cardiovascular and thermal controls were not affected by hypercapnia or by the injection of KY and MCPG in the LC. Conclusion: These data suggest that glutamate acting on ionotropic, but not metabotropic, receptors in the LC exerts an inhibitory modulation of hypercapnia-induced hyperpnea. © 2013 Scandinavian Physiological Society.

Role of brain nitric oxide in the cardiovascular control of bullfrogs

The goal of the present study was to determine if nitric oxide (NO) acting on the brain of bullfrog (Lithobates catesbeianus) is involved in arterial pressure and heart rate (HR) control by influencing sympathetic activity. We investigated the effect of intracerebroventricular injections of l-NMMA (a nonselective NO synthase inhibitor) on mean arterial blood pressure (MAP), HR and cutaneous vascular conductance (CVC) of pelvic skin after intravenous injection of α or β adrenergic blockers, prazosin or sotalol, respectively. Arterial pressure was directly measured by a telemetry sensor inserted in the aortic arch of animals. l-NMMA increased MAP, but did not change HR. This hypertensive response was inhibited by the pre-treatment with prazosin, but accentuated by sotalol. The effect of l-NMMA on MAP was also inhibited by i.v. injections of the ganglionic blocker, hexamethonium. Thus, NO acting on the brain of bullfrog seems to present a hypotensive effect influencing the sympathetic activity dependent on α and β adrenergic receptors in the periphery. © 2013 Elsevier Inc.

Inhibitory mechanism of the nucleus of the solitary tract involved in the control of cardiovascular, dipsogenic, hormonal, and renal responses to hyperosmolality

The nucleus of the solitary tract (NTS) is the primary site of visceral afferents to the central nervous system. In the present study, we investigated the effects of lesions in the commissural portion of the NTS (commNTS) on the activity of vasopressinergic neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei, plasma vasopressin, arterial pressure, water intake, and sodium excretion in rats with plasma hyperosmolality produced by intragastric 2 M NaCl (2 ml/rat). Male Holtzman rats with 15-20 days of sham or electrolytic lesion (1 mA; 10 s) of the commNTS were used. CommNTS lesions enhanced a 2 M NaCl intragastrically induced increase in the number of vasopressinergic neurons expressing c-Fos in the PVN (28 ± 1, vs. sham: 22 ± 2 c-Fos/AVP cells) and SON (26 ± 4, vs. sham: 11 ± 1 c-Fos/AVP cells), plasma vasopressin levels (21 ± 8, vs. sham: 6.6 ± 1.3 pg/ml), pressor responses (25 ± 7 mmHg, vs. sham: 7 ± 2 mmHg), water intake (17.5 ± 0.8, vs. sham: 11.2 ± 1.8 ml/2 h), and natriuresis (4.9 ± 0.8, vs. sham: 1.4 ± 0.3 meq/1 h). The pretreatment with vasopressin antagonist abolished the pressor response to intragastric 2 M NaCl in commNTS-lesioned rats (8 ± 2.4 mmHg at 10 min), suggesting that this response is dependent on vasopressin secretion. The results suggest that inhibitory mechanisms dependent on commNTS act to limit or counterbalance behavioral, hormonal, cardiovascular, and renal responses to an acute increase in plasma osmolality. © 2013 the American Physiological Society.

A role for histamine in cardiovascular regulation in late stage embryos of the red-footed tortoise, Chelonoidis carbonaria Spix, 1824

A chorioallantoic membrane artery in embryos of the red-footed tortoise, Chelonoidis carbonaria was occlusively cannulated for measurement of blood pressure and injection of drugs. Two age groups of embryos in the final 10 % of incubation were categorized by the ratio of embryonic body to yolk mass. All embryos first received cholinergic and β-adrenergic blockade. This revealed that β-adrenergic control was established in both groups whereas cholinergic control was only established in the older group immediately prior to hatching. The study then progressed as two series. Series one was conducted in a subset of embryos treated with histamine before or after injection of ranitidine, the antagonist of H2 receptors. Injection of histamine caused an initial phasic hypertension which recovered, followed by a longer lasting hypertensive response accompanied by a tachycardia. Injection of the H2 receptor antagonist ranitidine itself caused a hypotensive tachycardia with subsequent recovery of heart rate. Ranitidine also abolished the cardiac effects of histamine injection while leaving the initial hypertensive response intact. In series, two embryos were injected with histamine after injection of diphenhydramine, the antagonist to H1 receptors. This abolished the whole of the pressor response to histamine injection but left the tachycardic response intact. These data indicate that histamine acts as a non-adrenergic, non-cholinergic factor, regulating the cardiovascular system of developing reptilian embryos and that its overall effects are mediated via both H1 and H2 receptor types. © 2013 Springer-Verlag Berlin Heidelberg.

Efeitos da dexmedetomidina sobre o aparelho cardiovascular e a concentração plasmática da vasopressina em cães submeidos à isquemia e reperfusão renais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência dos genótipos / haplótipos das posições polimórficas -786T > C, 894G > T e Íntron 4b / a do gene NOS3 sobre o sistema cardiovascular e a atividade das enzimas antioxidantes em adultos submetidos ao treinamento físico aeróbio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Auditory stimulation with music influences the geometric indices of heart rate variability in response to the postural change maneuver

It is poor in the literature the behavior of the geometric indices of heart rate variability (HRV) during the musical auditory stimulation. The objective is to investigate the acute effects of classic musical auditory stimulation on the geometric indexes of HRV in women in response to the postural change maneuver (PCM). We evaluated 11 healthy women between 18 and 25 years old. We analyzed the following indices: Triangular index, Triangular interpolation of RR intervals and Poincar plot (standard deviation of the instantaneous variability of the beat-to beat heart rate [SD1], standard deviation of long-term continuous RR interval variability and Ratio between the short - and long-term variations of RR intervals [SD1/SD2] ratio). HRV was recorded at seated rest for 10 min. The women quickly stood up from a seated position in up to 3 s and remained standing still for 15 min. HRV was recorded at the following periods: Rest, 0-5 min, 5-10 min and 10-15 min during standing. In the second protocol, the subject was exposed to auditory musical stimulation (Pachelbel-Canon in D) for 10 min at seated position before standing position. Shapiro-Wilk to verify normality of data and ANOVA for repeated measures followed by the Bonferroni test for parametric variables and Friedmans followed by the Dunns posttest for non-parametric distributions. In the first protocol, all indices were reduced at 10-15 min after the volunteers stood up. In the protocol musical auditory stimulation, the SD1 index was reduced at 5-10 min after the volunteers stood up compared with the music period. The SD1/SD2 ratio was decreased at control and music period compared with 5-10 min after the volunteers stood up. Musical auditory stimulation attenuates the cardiac autonomic responses to the PCM.

Cardiovascular responses to injections of angiotensin II or carbachol into the rostral ventrolateral medulla in rats with AV3V lesions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Participation of the dorsal periaqueductal grey matter in the hypoxic ventilatory response in unanaesthetized rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Both alpha(1)- and alpha(2)-adrenoceptors in the Insular Cortex Are Involved in the Cardiovascular Responses to Acute Restraint Stress in Rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Combination Therapy for the Cardiovascular Effects of Perinatal Lead Exposure in Young and Adult Rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cardiovascular alterations at different stages of hypertension development during ethanol consumption: Time-course of vascular and autonomic changes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cardiovascular Complications following Chronic Treatment with Cocaine and Testosterone in Adolescent Rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

CRF1 and CRF2 receptors in the bed nucleus of the stria terminalis modulate the cardiovascular responses to acute restraint stress in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Response of cardiac autonomic modulation after a single exposure to musical auditory stimulation

The acute effects after exposure to different styles of music on cardiac autonomic modulation assessed through heart rate variability (HRV) analysis have not yet been well elucidated. We aimed to investigate the recovery response of cardiac autonomic modulation in women after exposure to musical auditory stimulation of different styles. The study was conducted on 30 healthy women aged between 18 years and 30 years. We did not include subjects having previous experience with musical instruments and those who had an affinity for music styles. The volunteers remained at rest for 10 min and were exposed to classical baroque (64-84 dB) and heavy metal (75-84 dB) music for 10 min, and their HRV was evaluated for 30 min after music cessation. We analyzed the following HRV indices: Standard deviation of normal-to-normal (SDNN) intervals, root mean square of successive differences (RMSSD), percentage of normal-to-normal 50 (pNN50), low frequency (LF), high frequency (HF), and LF/HF ratio. SDNN, LF in absolute units (ms (2) ) and normalized (nu), and LF/HF ratio increased while HF index (nu) decreased after exposure to classical baroque music. Regarding the heavy metal music style, it was observed that there were increases in SDNN, RMSSD, pNN50, and LF (ms (2) ) after the musical stimulation. In conclusion, the recovery response of cardiac autonomic modulation after exposure to auditory stimulation with music featured an increased global activity of both systems for the two musical styles, with a cardiac sympathetic modulation for classical baroque music and a cardiac vagal tone for the heavy metal style.