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PubMed1989

Action of the stereoisomers of medetomidine, in halothane-anesthetized dogs.

This study was designed to investigate the anesthetic-reducing and cardiovascular effects of the stereoisomers of medetomidine in halothane-anesthetized male beagles. Anesthesia was induced by mask inhalation of halothane in oxygen, followed by 2h equilibration period. The minimum alveolar anesthetic concentration of halothane which prevented the animals from moving in response to a painful stimulus (MAC of halothane) was determined and baseline hemodynamic function was assessed. Dl-Medetomidine, at 3 doses (1, 3 and 10 micrograms.kg-1) was administered via the right atrial port over 15 minutes while maintaining the dog at its individual MAC for halothane. Ten minutes later, hemodynamic parameters were reassessed. MAC determination was then repeated. In two separate sets of experiments, dogs (n = 5 each) were administered either the d- or the 1-enantiomer of medetomidine and the same procedure followed as described above. MAC for halothane significantly decreased following dl-medetomidine administration in a dose-dependent fashion. The d-isomer displayed similar MAC-reducing effects while the 1-isomer was without effect. Neither isomer changed the mean arterial pressure while only and d-isomer significantly decreased heart rate and cardiac output.

Adjuvants, Anesthesia↗
PubMed2002

Surgical and transcatheter (Amplatzer) closure of atrial septal defects: a prospective comparison of results and cost.

OBJECTIVE: To compare effectiveness, complications, and cost of Amplatzer with surgical atrial septal defect (ASD) closure. DESIGN: Prospective study. SETTING: Tertiary cardiac referral centre. PATIENTS: 43 consecutive patients (excluding non-UK residents) aged between 2.1 and 56.8 years (median 7) undergoing ASD closure. MAIN OUTCOME MEASURES: Procedural success, complications, regression of right ventricular dilatation (up to one year postprocedure), cost, inpatient stay, and home convalescent time. RESULTS: Amplatzer ASD closure was successful in 24 of 27 (89%) patients. Surgical closure was successful in all 19 cases. Cardiac complications affecting management occurred in three (11%) of the Amplatzer group (two procedural failures, one device embolisation) and 4 of 19 (21%) surgical patients (one pericardial pain, one global pericardial effusion requiring drainage, and one patient with anaemia requiring haematinics in addition to an incidental pericardial effusion and one further incidental pericardial effusion) (p = NS). There were complications that did not affect management in a further 5 of 19 surgical patients. There was no significant difference in regression of right ventricular dilatation by six months postprocedure (median right ventricular end diastolic diameter decrease: Amplatzer group 17.5%, surgical group 15.1%; median cardiothoracic ratio decrease: Amplatzer 7.9%, surgical 7.5%). Both hospital stay and home convalescent times were significantly shorter after Amplatzer closure (median hospital stay: Amplatzer one day, surgery six days; median convalescent time: Amplatzer two weeks, surgery 5.5 weeks). Median cost was similar for both groups (Amplatzer pound5375, surgical pound5412). CONCLUSIONS: Amplatzer ASD closure has a lower chance of success with a single procedure than surgery. Overall, there were more complications in the surgical group but the majority of these were minor and did not require any change in management. Resolution of right ventricular dilatation over the study period was similar for both techniques. Time spent in hospital and away from work or school was shorter for the Amplatzer group. The cost of both techniques was similar.

Adolescent↗
PubMed2006

Epicardial beating heart cryoablation using a novel argon-based cryoclamp and linear probe.

OBJECTIVE: Epicardial, beating heart cryoablation for the treatment of atrial fibrillation may be limited by heat from intracardiac blood flow. We therefore evaluated the ability to create cryolesions using an argon-based cryoclamp device, which temporarily occludes blood flow and facilitates transmurality. METHODS: Six mongrel dogs underwent sternotomy. A clamp employing a 10-cm argon-based linear cryoablation device was used epicardially to isolate the pulmonary veins and left atrial appendage. After clamping of lesions, the probe was removed from the cryoclamp device, and the remaining linear lesions, analogous to the Cox maze III, were performed. Pulmonary vein stenosis was evaluated with the use of magnetic resonance imaging. Left atrial function and pulmonary venous flow velocities were assessed with transesophageal echocardiography. Transmurality was confirmed both electrically and histologically. Animals were then put to death at 30 days. RESULTS: All acute and chronic cryoclamp lesions produced conduction block. There was no change in right (RPV) or left pulmonary vein (LPV) diameter on the basis of magnetic resonance imaging at baseline and at planned death (RPV-1, 19.6 +/- 2.9 mm vs 16.9 +/- 2.8 mm, P = .22; RPV-2, 13.2 +/- 2.0 mm vs 11.8 +/- 1.6 mm, P = .22; and LPV, 12.2 +/- 2.4 mm vs 11.2 +/- 1.9 mm, P = .30). Left atrial function and pulmonary venous flow velocities were unchanged. Tissue sections determined transmurality in 93% of cryoclamp lesions and 84% of linear ablations performed with the 10-cm malleable probe. CONCLUSIONS: Epicardial application of this cryoclamp device on the beating heart produced transmural lesions, which persisted 30 days. Linear epicardial cryoablation was not as effective as the cryoclamp device at producing consistent transmural lesions. This novel, versatile device may be useful in treating patients with atrial fibrillation on the beating heart without cardiopulmonary bypass.

Animals↗
PubMed1981

[The effect of tricuspid insufficiency on right ventricular performance in patients with valvular heart disease (author's transl)].

The hemodynamic effect of tricuspid insufficiency on right ventricular function was studied in 25 patients with rheumatic heart valve disease. 10 patients had mixed valve disease without tricuspid insufficiency (group A), and 15 patients had mixed mitral valve disease with tricuspid insufficiency (group B). Mitral valve area (1.76 vs. 1.66 cm2) and mitral regurgitant fraction (55 vs. 45%) were not significantly (p greater than 0.05) different between groups. Patients of group B revealed higher right atrial and right ventricular end-diastolic pressures than patients of group A. Right ventricular ejection fraction was lower in group B as compared to group A (44 vs. 52%, p less than 0.05). During ergometric exercise right atrial pressure was higher in group B as compared to group A (19 vs. 14 mm Hg, p less than 0.05), but mean pulmonary artery pressure (48 vs. 51 mm Hg, p greater than 0.05), cardiac index (3.3 vs. 3.31/min . mi2, p greater than 0.05) and stroke index (27 vs. 25 ml/m2, p greater than 0.05) were not significantly different. In mixed mitral valve disease associated with tricuspid regurgitation, right ventricular function is impaired when compared to mixed mitral valve disease of equal severity but without tricuspid regurgitation. Exercise induces a further augmentation of right atrial pressure in these patients with tricuspid regurgitation. We conclude, right atrial pressure elevation is not only the consequence of tricuspid regurgitation in group B but also the consequence of impaired right ventricular function. Impairment of right ventricular function is further augmented during exercise.

Adult↗
PubMed1983

Diagnosis of coronary stenosis by two-dimensional echographic study of dysfunction of ventricular segments during and immediately after pacing.

The adequacy of two-dimensional echocardiography during right atrial pacing for the detection and characterization of coronary artery stenosis was examined in 10 closed chest dogs. Pacing at successively higher rates up to 210 beats/min was carried out in the control state and again during a 70% left anterior descending coronary artery stenosis-induced with intracoronary plugs. Left ventricular short-axis echographic cross sections were obtained at several levels of the left ventricle. After computer-aided standardized subdivision, contractile function of the global section and its subsegments was characterized by computed systolic fractional area change percent and wall thickening percent. Ventricular segments supplied from the site of the 70% coronary stenosis were delineated in a low papillary level cross section by a myocardial contrast echographic technique, and these segments demonstrated significant dysfunction during pacing at 150 to 210 beats/min. Echographic observation of the involved segments immediately after pacing revealed a maximal depression of function 5 seconds after pacing, equivalent to dysfunction at peak pacing, with function returning to control levels within about 2 minutes. Both maximal pacing and early postpacing studies facilitated satisfactory discrimination of ischemic from normally perfused myocardial segments. These experiments show that right atrial pacing study with quantitative two-dimensional echocardiography may serve to detect and assess a coronary stenosis associated with minor or no cardiac dysfunction in the rest state.

Animals↗
PubMedDate not supplied

Quantitation of the global right ventricular function in children with normal heart and congenital heart disease: a right ventricular myocardial performance index.

Although the assessment of right ventricular (RV) function is important in the clinical management of children with congenital heart disease, available imaging techniques have been limited because of the complex geometry of the right ventricle. A new Doppler index combining systolic and diastolic time intervals (the Tei index) has been reported to be useful for the assessment of global RV function in adults. However, normal values in children, age-related changes, and the clinical utility of the Tei index with regard to congenital heart disease have not been demonstrated. The purpose of this study was to prospectively assess RV function in children with normal heart and congenital heart disease using the Tei index. The subjects included 150 healthy children and 43 patients with congenital heart disease (35 patients with atrial septal defects and 8 patients who had had a Senning operation). The index was defined as the sum of isovolumetric contraction time and isovolumetric relaxation time divided by ejection time and was measured from conventional RV outflow and inflow Doppler velocity profiles. The Tei index was not affected by age in healthy children (0.24 +/- 0.04). There was a significant difference in index rating between patients who had had a Senning operation (0.58 +/- 0.09) and healthy children (p < 0.01), but there was no significant difference between children with atrial septal defect (0.25 +/- 0.13) and healthy children. The Tei index is a feasible approach to use when assessing global RV function in children with congenital heart disease.

Adolescent↗
PubMed1992

Theoretical analysis of the relationship between the ratio of ventricular systolic elastance to diastolic stiffness and stroke volume.

The maintenance of adequate blood circulation requires a sufficient ventricular contractility; in addition, to eject blood, the ventricles must first receive a sufficient volume, requiring a low diastolic stiffness. A simplified cardiovascular model was used to derive formulae for stroke volume (SV) as a function of atrial pressure and the ratio of ventricular end-systolic elastance to end-diastolic stiffness. A more complex cardiovascular model was used to assess the ability of the expressions to predict stroke volume under various steady-state conditions. The predicted SV correlated linearly with the model SV over a wide range of diastolic stiffnesses and systolic elastance. The formulae predict that with fixed right atrial pressure the SV is proportional to the ratio of end-systolic elastance to end-diastolic stiffness (GR) for the right ventricle, but relatively insensitive to the ratio (GL) for the left ventricle provided that GL is greater than GR. Model simulations confirmed this. When the right atrial pressure was not fixed increases in GR with fixed GL reduced the right atrial pressure with little change in SV. Similarly, varying GL with fixed GR produced little change in SV. The ratios highlight the importance of diastole to cardiac function.

Diastole↗
PubMed1977

Pre and postoperative ventricular function in infants and children with right ventricular volume overload.

Hemodynamic and ventricular volume parameters were evaluated in 21 patients (24 studies) with total anomalous pulmonary venous return (TAPVR), 11 patients with secundum atrial septal defect (ASD), and eight patients who had complete correction of TAPVR or ASD. Right and left ventricular (RV and LV) volume parameters were calculated according to Simpson's rule and the area length methods, respectively. In infants with TAPVR, RV end-diastolic volume was larger than normal, but RV ejection fraction was significantly less than normal. LV end-diastolic volume and LV ejection fraction were all less than normal in infants with or without pulmonary hypertension, and the values did not correlate with the cardiorespiratory symptoms. In children with TAPVR or ASD, RV end-diastolic volume and output were higher than normal preoperatively and decreased to normal or near normal values postoperatively. The data suggest that pulmonary venous obstruction and/or RV failure are responsible for cardiorespiratory symptoms in infants with TAPVR and early surgical intervention is recommended in these patients.

Blood Volume↗
PubMed1992

[Risks of contraception and pregnancy in patients with congenital cardiopathies. Retrospective study on 108 patients].

108 women with congenital heart disease in child-bearing age (16-38 years, mean age 28) were followed up for a period of ten years. Possible complications of contraceptive methods, and incidence of full-term pregnancies, spontaneous abortions and cardiovascular complications during pregnancy and delivery, were considered. Half of these patients had a cyanotic congenital heart disease, 23 had left-to-right shunt mainly at atrial level, 18 had right and 14 left ventricular outflow tract obstruction. 60 women had previous surgical procedures for their congenital heart disease. 83% of the patients were in NYHA functional class I-II. No complications were found during oral contraceptive regimen during intrauterine device insertion with antibiotic prophylaxis, except for the development of pulmonary hypertension in one patient with an atrial septal defect. 146 pregnancies occurred, but only 89 were full-term. There was a high number of interrupted pregnancies, rarely for medical reasons. The incidence of spontaneous abortion was similar to that of normal population (18% versus 10-15%). Maternal cardiovascular complications were found in the 22% of the full-term pregnancies, but were well controlled by medical treatment. In conclusion, good family planning and pregnancies are possible in most young females with congenital heart disease. In the absence of cyanosis and pulmonary hypertension, oral contraception does not carry any particular risk. With appropriate medical care intrauterine devices may be an alternative in high risk patients. In the presence of a good cardiac function, a normal full-term pregnancy with an healty baby is the rule. A cesarean section is seldom needed.

Abortion, Spontaneous↗
PubMed1997

Internal atrial defibrillation: effect on sinus and atrioventricular nodal function and implanted cardiac pacemakers.

Internal atrial defibrillation (IAD) has been extensively evaluated for clinical efficacy but the need for concomitant demand pacing and the effect of IAD shocks on pacemaker function is not well studied. We prospectively evaluated: (1) the incidence of bradycardia as a result of IAD shocks; and (2) effect of these shocks on functioning of implanted cardiac pacemakers. Consecutive consenting patients with atrial fibrillation (AF) requiring cardioversion or undergoing electrophysiological study were selected for IAD. IAD shocks were delivered using the right ventricle to right atrium (RV-RA), right ventricle to superior vena cava (RV-SVC), right atrium to axillary patch (RA-AX), and right atrium to left pulmonary artery or coronary sinus (RA-LPA/CS) lead configurations. Mean RR interval before and after the shocks and the time interval from shock delivery to first QRS complex were analyzed for unsuccessful and successful shocks. Pacing and sensing function was analyzed in patients with previously implanted pacemakers. Twenty-five patients, 18 men, mean age 67.9 +/- 10 years were included in the study. A total of 305 shocks (264 unsuccessful, 41 successful) were analyzed. For unsuccessful shocks the mean post-IAD shock RR interval (795 +/- 205 ms) and the time to first post-IAD shock QRS complex (970 +/- 438 ms) were both significantly greater than the pre-IAD shock RR interval (685 +/- 131 ms, P < 0.001). The increase in post-IAD shock RR interval and time to first post-IAD shock QRS complex was seen with all four lead configurations used. With successful shocks the mean post-IAD shock sinus cycle length (1,105 +/- 450 ms) and time to first post-IAD shock QRS complex (1,126 +/- 443 ms) were both also significantly greater than the pre-IAD shock RR interval (766 +/- 172 ms). Nine patients (36%) had episodes of significant bradycardia after shock delivery. Shocks of up to 20 J using the RA-LPA/CS lead configuration did not affect pacemaker function. IAD can result in transient bradycardia related to sinus and atrioventricular nodal effects requiring backup ventricular pacing. Shocks can be safely delivered using RA-LPA or RA-CS lead configurations in patients with implanted bipolar cardiac pacemakers.

Aged↗
PubMed1993

[Is urapidil a venodilator?].

This study aimed to assess and compare the effects of urapidil and clonidine on right ventricular volumes and function in 20 physical status ASA III patients, with a borderline untreated essential hypertension and with or without chronic coronary artery disease. The patients were randomly assigned to two equal groups to receive either urapidil (0.4 mg.kg-1) or clonidine (2.5 micrograms.kg-1). Neither patient had congestive heart failure, valvular heart disease, previous myocardial infarction, nor was any being treated with beta-blocking agents or with amiodarone. Usual anti-anginal medication (nifedipine and isosorbide) was maintained up to the time of the procedure. Monitoring was obtained from ECG, Swan-Ganz catheter fitted out with a fast response-thermistor, and radial artery cannula. Blood samples were withdrawn for plasma atrial natriuretic factor determination. Thirty minutes after catheter insertion, baseline data were collected in supine and 45 degrees head-up tilt positions. Following urapidil or clonidine i.v. injection, three series of measurements (3, 8 and 13 min) were made in supine and tilt positions according to a randomized sequence. The two groups were similar with regard to age, weight, height, coronary artery disease and treatment. Urapidil and clonidine elicited a similar decrease in mean arterial pressure of 14% in supine position and 20% in head-up tilt position, combined with an exclusive decrease in systolic index i.e. not associated with a change in peripheral vascular resistances. Despite the decrease in arterial pressure, heart rate remained unchanged. Right ventricular ejection fraction was maintained after both urapidil and clonidine, however end-diastolic and end-systolic volumes decreased, with no modification by tilting.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Natriuretic Factor↗
PubMed2001

Left ventricular aneurysm repair in rats: structural, functional, and molecular consequences.

OBJECTIVES: This study examined the effects of aneurysm repair in a rat model of myocardial infarction on functional indices and on the spatiotemporal distribution of cardiac contractile protein and natriuretic peptide messenger RNA. METHODS: In a rat infarct model, expanded left ventricular aneurysms were plicated 4 weeks after infarction. At 30 weeks, transverse heart sections were taken at 4 levels (apex [level 1] through base [level 4]) and assessed by in situ hybridization histochemistry to determine regional messenger RNA levels of pre-pro-atrial natriuretic peptide, cardiac alpha-actin, skeletal alpha-actin, myosin light chain-2v, and beta-myosin heavy chain. RESULTS: Rats with plicated left ventricular aneurysms had reduced left ventricular endocardial circumference (19%, P <.005), lower heart weight ratio (31%, P <.05), left ventricular end-diastolic pressures (51%, P <.05), and increased +/-dP/dt (34%-38%, P <.05). Cardiac messenger RNA levels of pre-pro-atrial natriuretic peptide were reduced in the septum (levels 2 and 3), and skeletal alpha-actin levels were reduced in the septum and left ventricular free wall of plicated rats (level 3). beta-Myosin heavy chain levels were markedly reduced in peri-infarct regions of the left ventricular free wall, septum, and right ventricle in plicated rats at level 4, whereas myosin light chain-2v levels were reduced at levels 2 and 4 in the left ventricular free wall and at level 4 in the right ventricle. CONCLUSIONS: Plication of left ventricular aneurysm after infarction in the rat significantly reduced cardiac hypertrophy, improved cardiac function, and reduced the upregulation of pre-pro-atrial natriuretic peptide and both fetal and adult contractile protein isoforms associated with cardiac hypertrophy.

Actins↗
PubMed1997

[Hemodynamic effects of right ventricular outflow pacing].

The effects of right ventricular outflow pacing were studied in 13 patients (mean [+/-SD] 69.8 +/- 8.2 years old). All patients received DDD pacemakers except two patients with implanted VVI pacemakers who had chronic atrial fibrillation. Cardiac output and pulmonary capillary wedge pressure were measured by Swan-Ganz catheter. Pacing rate was fixed at 70-80/min and atrioventricular delay was fixed at 165 msec. When the pacing site was changed from the right ventricular apex to the right ventricular outflow during right ventricular pacing in 11 patients, cardiac output increased from 3.3 +/- 0.6 to 3.4 +/- 0.5 l/min (p < 0.001), and wedge pressure decreased from 9.3 +/- 1.9 to 8.8 +/- 2.0 mmHg (p < 0.05). When the pacing site was changed from the right ventricular apex to the right ventricular outflow during atrioventricular pacing in eight patients, cardiac output increased from 3.9 +/- 0.4 to 4.0 +/- 0.4 l/min (p < 0.05), and wedge pressure decreased from 7.1 +/- 2.3 to 6.6 +/- 2.1 mmHg (p < 0.05). When the pacing site was changed from the right ventricular apex to the right ventricular outflow in seven patients with ejection fraction (EF) greater than 55%, cardiac output increased from 3.6 +/- 0.5 to 3.7 +/- 0.4 l/min (p < 0.05), and in four patients with EF less than 55%, it increased from 2.9 +/- 0.4 to 3.0 +/- 0.4 l/min (p < 0.01). Cardiac function was improved by right ventricular outflow pacing compared to right ventricular apex pacing regardless of the pacing mode or cardiac function.

Aged↗
PubMed2000

Late arrhythmia in adults with the mustard procedure for transposition of great arteries: a surrogate marker for right ventricular dysfunction?

OBJECTIVE: To examine the relation between ventricular dysfunction and late clinical arrhythmia in adults who underwent the Mustard procedure for transposition of the great arteries. DESIGN: Observational study based on periodic outpatient assessment of biventricular function. SETTING: Tertiary referral centre. INTERVENTIONS: Analysis of data from 12 lead ECGs, echocardiography, exercise radionuclide ventriculography, and magnetic resonance imaging. MAIN OUTCOME MEASURES: Clinical outcome and late onset clinical arrhythmia during follow up. ECG and ventricular function indices obtained before arrhythmia onset were used for analysis. RESULTS: 51 patients (mean (SD) age 25.7 (5.0) years) fulfilled entry criteria at a mean of 23.4 (4.0) years after the Mustard procedure. Late arrhythmia occurred in 11 (22%): sustained atrial flutter/fibrillation in 10, ventricular tachycardia in one. Compared with patients who remained arrhythmia free, patients with arrhythmia had longer QRS (129 (26) v 112 (16) ms, p = 0.01), greater QT dispersion (107 (28) v 51 (24) ms, p < 0.001), and increased ratio of right to left ventricular end diastolic diameter (2.4 (0.9) v 1.7 (0.7), p = 0.02), but no difference in wall thickness. Systemic ejection fraction was also reduced in the arrhythmia subgroup (at rest: 34.1 (13)% v 47 (16)%, p = 0.04; during exercise: 37.8 (12)% v 52 (17)%, p = 0.03). QRS duration correlated with right ventricular end diastolic diameter (r = 0.59, p < 0.001), suggesting a possible mechano-electric relation after the Mustard procedure. QT dispersion was the only predictor of clinical arrhythmia in multivariate analysis. CONCLUSIONS: Impaired ventricular function in adults with the Mustard procedure for transposition of the great arteries relates to clinical arrhythmia. Late atrial flutter/fibrillation may be a surrogate marker for ventricular dysfunction, and these patients may also be at risk of ventricular tachycardia.

Adult↗
PubMed1986

Effects of elevated coronary sinus pressure on left ventricular function after the Fontan operation. An experimental and clinical correlation.

An experimental model was devised to evaluate the effects of elevated coronary sinus pressure on left ventricular performance. Thirteen mongrel dogs were used. The coronary sinus was cannulated and its entire blood flow diverted into a reservoir. The pressure in the coronary sinus was increased from 5 to 25 torr by elevating the drainage reservoir in a stepwise fashion. Cardiac index, coronary arteriovenous difference, rate of rise of left ventricular pressure, left ventricular systolic time intervals, and coronary blood flow were measured. When the coronary sinus pressure reached 15 torr, there was a significant decrease in cardiac index (3.60 +/- 0.5 to 2.70 +/- 0.6 L/min/m2, p less than 0.001), coronary blood flow (13.7 +/- 3.1 to 7.0 +/- 2.1 ml/min, p less than 0.001), rate of rise of left ventricular pressure (1,567 +/- 275 to 1,331 +/- 314, p less than 0.05), and an increase in coronary arteriovenous difference (62.8% +/- 9.3% to 70.5% +/- 5.4% saturation, p less than 0.03). These experimental results were correlated with postoperative catheterization findings in 24 patients with the Fontan procedure. Patients with a mean right atrial pressure less than 15 torr had a left ventricular ejection fraction of 93% +/- 6% of predicted, whereas patients with a right atrial pressure of 15 torr or more had a left ventricular ejection fraction of 75% +/- 13% of predicted (p less than 0.001). These experimental and clinical data strongly suggest that elevated coronary sinus pressure has deleterious effects on ventricular function after the Fontan procedure. Modifications of the procedure, such as using the rudimentary right ventricle when feasible or diverting coronary sinus flow to the pulmonary venous atrium, might decrease coronary sinus hypertension and improve long-term results.

Animals↗
PubMed1997

Prejunctional neuropeptide Y receptors in human kidney and atrium.

The aim of our study was to characterize functionally prejunctional neuropeptide Y (NPY) receptors in human and rabbit renal cortex, as well as in human right atrium. Segments of human atrial appendages and of human and rabbit renal cortex were preincubated with [3H]noradrenaline, superfused with Krebs-Henseleit solution and stimulated electrically in superfusion chambers. The stimulation-induced outflow of radioactivity was taken as an index of endogenous noradrenaline release. The effects of subtype-selective NPY analogs on the stimulation-induced noradrenaline release were studied. NPY, its endogenous analog, peptide YY, and its C-terminal fragment, NPY13-36, but not its analog, [Leu31,Pro34]NPY, concentration dependently (1-100 nM) inhibited [3H]noradrenaline release in all tissues studied. NPY-induced inhibition of [3H]noradrenaline release in human and rabbit kidney was abolished by pretreatment with pertussis toxin. We conclude that prejunctional inhibition of noradrenaline release in human heart and human and rabbit kidney occurs through NPY receptors of the Y2 subtype, which appear to couple to a pertussis toxin-sensitive G protein.

Animals↗