The Effects of Changes in Left Ventricular Pressure on Respiratory Activity in Anaesthetized Dogs

Crisp, A. J.; Tutt, S. M.; McGregor, Keith; Hainsworth, R.

doi:10.1113/expphysiol.1989.sp003272

Cited by 10 publications

(9 citation statements)

References 22 publications

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“…For example, Crisp and colleagues (7) reported that elevating LVP in anesthetized dogs decreased phrenic nerve activity, an index of ventilatory drive to the diaphragm. In a separate study, Crisp and coworkers (6) noted that elevating RVP had no effect on ventilation.…”

Section: Discussionmentioning

confidence: 99%

Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats

Schlenker

Tamura²,

Gerdes³

2003

Journal of Applied Physiology

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der-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats. J Appl Physiol 95: 2292-2298, 2003. First published August 8, 2003 10.1152/japplphysiol. 00594.2003.-Spontaneously hypertensive heart failure (SHHF) rats develop hypertension and heart failure. We hypothesized that induction of hyperthyroidism should accelerate development of heart failure in male SHHF rats. Male and female SHHF rats received diets containing desiccated thyroid glands (DTG) or a control diet for 8 wk. Male and female Wistar-Kyoto rats were used as normotensive controls. DTG treatment reduced body weight in male, but not female, SHHF rats but increased body temperature and heart weight-to-body weight ratio in both genders. In DTGtreated male SHHF rats, serum triiodothyronine levels doubled relative to SHHF controls, whereas O2 consumption increased in DTG-treated SHHF rats. Frequency of breathing in air increased in DTG-treated female rats, and ventilation increased in DTG-treated male rats. Ventilatory equivalents exhibited gender differences in SHHF rats, were decreased in both genders by DTG treatment, and reached levels similar to those of Wistar-Kyoto rats. DTG increased heart rate, right ventricular pressure, and contractility in both genders and increased left ventricular pressure in SHHF male rats. These results refute our hypothesis and suggest that cardiopulmonary function of SHHF male rats may be improved by DTG treatment.hypertension; sick euthryoid syndrome; hyperthyroidism SPONTANEOUSLY HYPERTENSIVE heart failure (SHHF) rats were originally derived from a cross between the spontaneously hypertensive rat (SHR) and the Koletsky obese rat. Subsequently, these animals were bred with SHR-N (an SHR colony at the National Institutes of Health) (27). Lean male SHHF rats die between 15 and 20 mo of age, and lean females die between 22 and 26 mo of age. Although gender differences in the development of heart failure and hypertension have been examined in this strain (11,12,18,28,36), control of breathing has not been investigated.An additional stressor on the cardiopulmonary system is thyroid hormone dysfunction. For example, hyperthyroidism increases the metabolic demands of the body and stresses the cardiovascular and respiratory systems (22,29). In contrast, patients with heart failure can actually exhibit a "sick euthryoid" syndrome, characterized by decreased or normal levels of triiodothyronine (T 3 ) and increased levels of reverse T 3 (9, 23, 35). The possibility of using thyroid hormone replacement as a therapeutic measure has been approached in patients with heart failure (13, 23). Thus, increasing thyroid levels in SHHF rats may actually improve their cardiopulmonary status.In this study, we investigated the effects of experimentally induced hyperthyroidism in male and female SHHF rats on control of breathing and cardiac function. Gender-matched Wistar-Kyoto (WKY) rats were used as normotensive, euthryoid controls. We hypothesized that the combined effects of hyperthyroidism and hypertension would ...

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Section: Discussionmentioning

confidence: 99%

Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats

Schlenker

Tamura²,

Gerdes³

2003

Journal of Applied Physiology

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“…Cap treatment, however, did not prevent the development of periodic breathing, a finding also described in SHR (4). Additional mechanisms by which Cap may maintain ventilation is altering reflex responses to elevated blood pressure (10). Thus the decrease of blood pressure in Cap-treated SHHF rats may be one way that ventilation was maintained relative to the increase in ventilation in DI-treated rats.…”

Section: Discussionmentioning

confidence: 82%

“…In diabetic patients with hypertension, endogenous inhibitors of NO synthase (NOS) can decrease the production of NO that acts as a vasodilator (16,39). In addition to effects on the vasculature, NO affects control of breathing directly by modulating neurotransmitter function in the carotid body and brain stem sites and/or possibly indirectly by decreasing blood pressure (10,12,22,30,32).To determine the efficacy of ACE inhibitors and Arg on diabetes and hypertension, we utilized the obese male spontaneously hypertensive heart failure (SHHF)/MccGmi-fa cp rat that develops noninsulin-dependent diabetes mellitus, obesity, hypertension, heart failure, and renal dysfunction (15,22,28,38). The "fa cp " designation reflects that the fatty (fa) gene mutation and corpulent (cp) obesity gene mutations are allelic.…”

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confidence: 99%

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Effects of long-term captopril andl-arginine treatment on ventilation and blood pressure in obese male SHHF rats

Schlenker

Kost

Likness

2004

Journal of Applied Physiology

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Schlenker, E. H., C. K. Kost, Jr., and M. M. Likness. Effects of long-term captopril and L-arginine treatment on ventilation and blood pressure in obese male SHHF rats. J Appl Physiol 97: 1032-1039, 2004. First published May 14, 2004 10.1152/japplphysiol.00255.2004We investigated the effects of captopril (Cap) and L-arginine (Arg) on hypertension and cardiopulmonary function. Our hypothesis was that Cap therapy or Arg will improve cardiopulmonary risk factors for hypertension and hypoventilation in the obese spontaneously hypertensive heart failure rat, which is characterized by hypertension, obesity, and disorders of lipid and carbohydrate metabolism. For the first study, one group of rats received Cap in drinking water, and a second group received deionized water (DI). For the second study, rats were further subdivided. Some Cap-treated rats continued on this treatment, and the other half were now given DI to determine whether there would be residual effects of Cap treatment. A subgroup of rats who had received DI was then given Arg, whereas the rest remained on DI. In the first study, Cap-treated rats exhibited decreases in systolic and diastolic blood pressures, frequency of breathing, and minute ventilation, but ventilatory control was maintained. In contrast, blood pressures and relative ventilation to metabolism were higher in the DI-treated group. Removal of Cap increased blood pressure and decreased tidal volume while these rats maintained frequency. Although Arg-treated rats did not exhibit a decrease of blood pressure, ventilation was maintained in this group by preserving tidal volume. Thus Cap and Arg affected ventilation through different mechanisms independent of blood pressure.spontaneously hypertensive heart failure rat; hypertension; metabolic syndrome X; ventilatory equivalent; frequency OBESITY, DIABETES, AND HYPERTENSION are major risk factors for cardiopulmonary and renal disease (1,7,9,18,41). The concurrence of these risk factors is also known as the metabolic syndrome X (8, 49). In addition to metabolic and cardiovascular complications, individuals with metabolic syndrome X can also present with hypoventilation during sleep and obstructive sleep apnea (8, 47).Hypertension and congestive heart failure originate from the activation of multiple neuroendocrine systems, including the renin-angiotensin (Ang), endothelin, and atrial natriuretic peptide systems (13, 23-25, 41, 51). One in four adults develops hypertension and is at increased risk of stroke, coronary disease, congestive heart failure, and end-stage renal disease (2). Ang-converting enzyme (ACE) inhibitors are regarded as the first line of hypertensive therapy in diabetic patients due to their protective effects on the cardiovascular and renal systems (23,27,45). Ideally, treatment of hypertension would normalize blood pressure early in the disease, thus decreasing the incidence of cardiovascular-associated morbidity and mortality. Another agent that has been shown to decrease blood pressure is L-arginine (Arg) (50), a substrate ...

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“…The technique used for applying a mechanical stimulation to left ventricular receptors has been critically discussed by Crisp, Tutt, McGregor & Hainsworth (1989). The main points are that the pressure applied to the aortic root did not distend the vast majority of aortic baroreceptors or chemoreceptors because the ascending aorta was tied onto a cannula and the pressure in the pouch of the aorta, outside the cannula, was separated from the applied aortic root pressure.…”

Section: Eph 74 29mentioning

confidence: 99%

The Influence of Left Ventricular Pressure on the Vascular Responses to Changes in Carotid Sinus Pressure in Anaesthetized Dogs

Vukasovic¹,

Tutt²,

Crisp³

et al. 1989

Exp Physiol

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SUMMARYThe aim of this study was to determine whether the degree of stimulation of left ventricular receptors influenced the sensitivity of the carotid sinus baroreceptor reflex. In anaesthetized dogs, the stimulus to left ventricular receptors was changed by changing aortic root and hence ventricular systolic pressure, using a preparation in which the applied pressure did not distend the aortic arch and in which left atrial pressure was controlled. A large step increase in either carotid or left ventricular pressure resulted in vasodilatation both in a perfused hindlimb and in the remainder of the systemic circulation and resulted in a reduction in the response to a change in pressure in the other area. The stimulus-response curves, relating limb and systemic perfusion pressures to small step changes in carotid sinus pressure, were displaced downwards at high left ventricular pressures. However, the curves remained parallel indicating the absence of an interactive effect. These results indicate that the vascular responses to changes in carotid and ventricular pressures show simple additive summation.

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The Effects of Changes in Left Ventricular Pressure on Respiratory Activity in Anaesthetized Dogs

Cited by 10 publications

References 22 publications

Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats

Gender-specific effects of thyroid hormones on cardiopulmonary function in SHHF rats

Effects of long-term captopril andl-arginine treatment on ventilation and blood pressure in obese male SHHF rats

The Influence of Left Ventricular Pressure on the Vascular Responses to Changes in Carotid Sinus Pressure in Anaesthetized Dogs

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