Maximum Diastolic Blood Pressure Research Articles

Autonomic nervous system function assessed by analysis of heart rate variability at rest and during exercise in hypertensive and normotensive subjects

P-480 Key Words: Autonomic Nervous System Activity, Heart Rate Variability, Pressure Response To Exercise

Arterial stiffness is associated with orthostatic hypotension in elderly subjects with history of falls.

To test the hypothesis that impaired hemodynamic orthostatic changes commonly observed in the elderly may be related to age-related increase in arterial wall stiffness. Convenience sample of consecutive patients admitted for falls. Acute- and intermediate-care geriatric ward of a French hospital. Fifty-seven elderly patients (46 women) consecutively admitted to a geriatric ward with a history of recent falls. Orthostatic hypotension (OH) was assessed using blood pressure measurements in the supine position and 1, 2, and 3 minutes after standing. Arterial wall stiffness was assessed using upper-limb and aortic pulse-wave velocities, measured with an external pressure transducer connected to a computer. OH was present in 18 patients with a mean age+/-standard deviation of 85.4+/-7.6 (5 men, 13 women) and absent in 39 patients aged 83.7+/-6.2 (6 men, 33 women). Upper-limb pulse-wave velocity was significantly higher, by 16%, in patients with OH than those without (9.91 vs 8.53 m/s; P<.02). Significant correlations were found between upper-limb pulse-wave velocity and systolic blood pressure changes after 1 minute of standing (r=0.263, P<.05) and maximal diastolic blood pressure change after standing (r=0.351, P<.01). Upper-limb arterial wall stiffness was significantly greater in elderly patients with OH than in patients without OH and was significantly related to blood pressure changes after standing. These results highlight the possible role of age-related changes in the arterial tree in the hemodynamic response to orthostatic challenges.

Relationship between 24-H blood pressure and sleep disordered breathing in a normotensive community sample

Sleep disordered breathing (SDB) and hypertension are commonly associated. In this study, we assessed how longitudinal measures of SDB predict a 24-h ambulatory blood pressure monitoring (ABPM) profile. Participants ( n = 82) were recruited from a community-based urban (26% African American) sample and included family members of patients with laboratory diagnosed SDB (cases) and family members of neighborhood control subjects evaluated at baseline and at 5 years. Nearly all participants were normotensive and were not receiving therapy for SDB. During both examinations, the respiratory distress index (RDI) was assessed with overnight in-home polysomnography. Seated blood pressure (BP) was assessed at a baseline examination (t 1) and after a 5-year follow-up period (t 5), when 24-h ABPM also was performed. The change in RDI (t 5−t 1) over 5 years was significantly associated with 24-h mean systolic blood pressure (SBP) ( P = .04), 24-h maximum diastolic blood pressure (DBP) ( P = .03), sleep mean SBP ( P = .05), sleep mean DBP ( P < .05), and sleep maximum SBP ( P = .02). Regression analysis revealed that average 24-h mean arterial pressure (MAP) and mean 24-h DBP were each best predicted by change in RDI, explaining 5% of the variance in these 24-h BP readings, and by current smoking status. After accounting for these variables, BP was not predicted by any of the other potential confounders (all P > .10). Mean RDI (averaged between t 5 and t 1) was associated with mean MAP, mean SBP, and maximal SBP measured during sleep. This study documents for the first time the association between changes in sleep apnea activity and BP and in a community-based normotensive sample. Further long-term evaluation of the effects of these findings and the long-term consequences of hypertension are needed.

Intensification of fetal and maternal surveillance in pregnant women with hypertensive disorders

Objective: To examine the need to intensify fetal and maternal surveillance in pregnant women with mild pregnancy hypertension. Methods: The multi-center cohort study in 2413 healthy nulliparae analyzed differences in hypertension-related adverse events (small-for-gestational age, perinatal mortality, eclampsia, abruptio placentae and HELLP syndrome) according to maximum diastolic blood pressure and proteinuria. Results: Compared to the reference group (diastolic blood pressure 70–85 mmHg) ( n=1882) the relative risks of adverse fetal and maternal outcome in 34 proteinuric hypertensive women were 8.9 (95% CI 3.3–24.1) and 41.5 (95% CI 9.7–178.4), respectively. In 203 non-proteinuric women with a maximum diastolic blood pressure of ≥95 mmHg only the relative risk of adverse maternal outcome was increased (11.6, 95% CI 3.1–42.8), but it was not increased in 230 non-proteinuric women with a maximum diastolic of 90 mmHg. Conclusions: Intensified surveillance in women with mild pregnancy hypertension is not indicated and should be reserved for groups with increased fetal and maternal risk.

Impairment of muscle energy metabolism in patients with sleep apnoea syndrome

Impairment of muscle energy metabolism has been demonstrated in normal subjects with chronic hypoxaemia (altitude chronic respiratory failure). The purpose of this study was to verify the hypothesis that a comparable condition could develop in patients with sleep apnoea syndrome (SAS), considering that they are exposed to prolonged and repeated hypoxaemia periods. Muscle metabolism was assessed in 11 patients with SAS performing a maximal effort on cycloergometer. In comparison with normal subjects, SAS patients reached lower maximal loads [144 ± 7 vs. 182 ± 10 W ( P<0·005)] and lower peak oxygen uptakes [26·4 ± 1·2 vs. 33·2 ± 1·4 ml kg −1 min −1 ( P<0·005)]. Abnormal metabolic features were found: maximal blood lactate concentration was significantly lower than in normal subjects [0·034 ± 0·004 vs. 0·044 ± 0·002 mmol 1 −1 W −1 ( P<0·05)]; and lactate elimination rate, calculated during a 30-min recovery period, was reduced [0·127 ± 0·017 vs. 0·175 ± 0·014 mmol 1 −1 min −1 ( P<0·025)]. The extent of these anomalies correlated with the severity of SAS. The patients also showed higher maximal diastolic blood pressures than normal subjects [104 ± 5 vs. 92 ± 4 mmHg ( P<0·05)]. These results can be interpreted as indications of an impairment of muscle energy metabolism in patients with SAS. Decrease in maximum blood lactate concentration suggests an impairment of glycolytic metabolism, while decrease in the rate of lactate elimination indicates a defect in oxidative metabolism. Since no respiratory pathology apart from SAS was found in this group of patients, it seems legitimate to link the genesis of these impairments to repeated bouts of nocturnal hypoxaemia.

The tolerability and safety of valproate sodium injection given as an intravenous infusion

Patients with epilepsy may sometimes require antiepileptic drugs (AEDs) parenterally. This study assessed the safety and tolerability of valproate sodium injection (IV valproate) (Depacon, Abbott Laboratories, Abbott Park, IL), given by intravenous infusion, as replacement therapy for oral valproate in a placebo-controlled trial involving stable epilepsy inpatients on steady doses of divalproex sodium (DVPX). Thirty-four patients received IV valproate and oral placebo, and 17 received IV placebo and oral DVPX (Depakote, Abbott Laboratories) every 6 hours for 4 days. The dose of IV valproate was the same (milligram for milligram) as that of previous oral DVPX. Concomitant AEDs were continued as usual. No serious adverse events were observed with IV valproate, nor were any clinically significant differences found between study groups for changes in average, minimum, or maximum systolic or diastolic blood pressure or heart rate. Positional changes caused no significant group differences in these variables, and no evidence of either acute or cumulative cardiotoxicity was found. The only changes found in laboratory values were increased SGOT and SGPT levels in the IV valproate group, compared with decreases in the control group ( P = 0.014 and 0.001, respectively). In conclusion, intravenous sodium valproate appears to be a well-tolerated substitute for an equivalent dose of oral valproate.

The Rubenesque pregnancy: a progression towards higher blood pressure correlates with a measure of endogenous and exogenous insulin levels.

Women with gestational diabetes tend to progress to noninsulin-dependent diabetes (NIDDM) with a high cumulative incidence relative to the general population. These women have also been shown to be insulin resistant and may represent a variant of the insulin resistance syndrome or Syndrome X. Our previous studies indicated that administered insulin was associated with an increase in blood pressure in women with gestational diabetes, raising the question that insulin levels per se contribute to blood pressure in these women. We developed a means by which the insulin levels of a given pregnant individual might be estimated called the Fraction of Circulating Insulin Level Relative to Normal (FOCILRN = C-PEPTIDE/2.0 + TOTAL DAILY INSULIN DOSE/CALCULATED DAILY INSULIN REQUIREMENT BASED ON WEIGHT AND GESTATIONAL WEEK). The formula was applied to 15 nonhypertensive pregnant women of comparable obese phenotype (Rubenesque) with varying degrees of glucose tolerance (4 normal, 5 gestational diabetes treated with diet alone, 4 gestational diabetes treated with insulin, and 2 noninsulin-dependent diabetes). Blood pressure was quantified at the beginning of the study (gestational weeks 24-34) and again 4-8 weeks later using a 24-hr monitor. Correlation analysis was used to test for a relationship between the FOCILRN and blood pressure. The increase in mean arterial pressure was found to be continuous and linear with increasing insulin exposure as quantified by FOCILRN. The correlation was significant for all subjects (r = 0.961, p < 0.001) and remained significant even with removal of patients with NIDDM (r = 0.857, p < 0.001). The nighttime heart rate, systolic and diastolic blood pressures were found to be significantly correlated with FOCILRN (r = 0.651, p < 0.01, r = 0.724, p < 0.001, and r = 0.831, p < 0.001, respectively). The difference between the maximum and minimum diastolic blood pressure values between 12:00 AM and 6:00 AM between sessions 1 and 2 significantly differed among the groups with women on insulin having the highest FOCILRN having the least variation in blood pressure. In nonhypertensive women of obese phenotype (Rubenesque), increasing insulin exposure is associated with increasing mean arterial blood pressure and less variability of nocturnal blood pressure. These data provide support for the hypothesis that insulin may mediate blood pressure response in genetically vulnerable individuals. The identification of the Rubenesque phenotype during gestation may be a clinically useful marker for individuals at risk for Syndrome X.

Blood Pressure Ranges in Premature Infants: II. The First Week of Life

To examine the arterial blood pressure in the first week of life in a healthy premature population. Population-based cohort study. Three intensive care nurseries in central New Jersey. Premature infants with birth weights less than 2000 g. We documented daily maximum and minimum systolic and maximum and minimun diastolic blood pressures during the first 7 days of life. To examine the effects on the ranges of blood pressure, we identified four groups of infants: (1) healthy infants without any of the major risk factors (n = 193); (2) infants who were mechanically ventilated but free of any of the other conditions (n = 225); (3) infants with histories of maternal hypertension or preeclampsia (n = 38) and (4) infants with low Apgar scores (less than 3 at 1 minute and less than 6 at 5 minutes) regardless of the presence of other conditions (n = 86). Blood pressure increased steadily in the first week of life in all four groups. There was no relationship between any of the four blood pressure variables, or trends in blood pressure over time, with birth weight, gender, or race. Regression equations (based on all infants with available data) for blood pressure ranges by day of life revealed that the maximum systolic blood pressure increased by 2.6 mm Hg/d, the minimum systolic blood pressure increased by 1.8 mm Hg/d,the maximum diastolic blood pressure increased by 2.0 mm HHg/d, and the minimum diastolic blood pressure increased by 1.3 Hg/d. Infants with birth asphyxia and ventilated infants had significantly lower systolic and diastolic blood pressures than healthy infants.

Insulin sensitivity, sympathetic activity, and cardiovascular reactivity in young men

The present study was undertaken to examine the relationships between insulin sensitivity, blood pressure (BP), and cardiovascular reactivity, and to assess sympathetic nervous system influence. Insulin sensitivity (GDR/I; euglycemic glucose clamp technique) was related to BP and heart rate (HR) in different situations in 40 healthy young men: in the laboratory, during a mental arithmetic stress test, and during baseline conditions at home. GDR/I correlated with supine diastolic BP in the laboratory and with maximum diastolic BP during mental stress (r = -0.46, P = .003; r = -0.62, P = .0001, respectively), but not so strongly with diastolic BP measured at home (r = -0.29, P = .09). Diastolic BP during stress and body mass index were the only independent explanatory variables of GDR/I in multiple regression analysis (multiple R = 0.71, R2 = 0.50, P < .0001). GDR/I and systolic BP were not significantly correlated at any time. GDR/I correlated negatively with HR in the laboratory and with maximum HR during mental stress, but not with HR at home. Maximum plasma epinephrine during stress correlated with stress BP and HR (r = 0.53, P = .001; r = 0.70, P < .0001, respectively) and negatively with GDR/I (r = -0.36, P < .05). In the present study, GDR/I is related to diastolic but not to systolic BP, and more closely correlated to diastolic BP and HR measured during mental stress than to diastolic BP and HR during baseline conditions at home.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood pressure effects of acute intravenous renin or oral angiotensin converting enzyme inhibition in essential hypertension

To assess the participation of the renin-angiotensin system in the blood pressure regulation of essential hypertensive patients through acute specific renin inhibition. Fifty-three consecutive untreated hypertensive patients (mean +/- SD age 55 +/- 10 years, 42 male) were investigated on their usual sodium diet in a 3-h protocol. The first 11 patients did not receive any drug, the following 20 patients ingested a single oral dose of captopril (1 mg/kg) and the last 22 patients received a renin inhibitor infusion (remikiren; 1 mg/kg over 60 min). The maximum diastolic blood pressure fall was comparable in the two treated groups. Diastolic blood pressure changes analysed as area under the curve were similar for both drugs (overall F1,40 = 1.26, P = 0.27). Even though the baseline renin levels were within the narrow range 5-80 pg/ml, the diastolic blood pressure fall analysed as area under the curve from time 32 min to time 60 min was significantly correlated with the baseline active renin level in both groups (remikiren r = 0.44, P < 0.05; captopril r = 0.47, P < 0.05). The plasma active renin levels were significantly increased at 30, 90 and 120 min in both groups, and the maximum active renin levels were significantly correlated with the baseline active renin level (remikiren r = 0.62, P < 0.01; captopril r = 0.66, P < 0.01). The plasma prorenin levels did not change. This study suggests that acute renin inhibition and acute angiotensin converting enzyme inhibition similarly decrease the blood pressure and increase the plasma active renin levels. Acute blockade of the renin-angiotensin system at its initial step by a renin inhibitor can therefore be used to investigate the renin dependence of the blood pressure in essential hypertension.

Does diurnal variation in blood pressure exist in CAPD patients?

The existence of diurnal variation in CAPD remains controversial. We therefore attempted to delineate the blood-pressure (BP) pattern in CAPD patients by ambulatory blood-pressure monitoring (ABPM). Initially ABPM was performed in 31 patients (21 M, 10 F), mean age 65.4 years (26-87) using the Spacelabs model 90207. The maximal normal BP preset on the recorder was 140/90 mmHg. Daytime and night-time readings, recorded every 30 min, were defined as those from 0600 to 2100 and 2100 to 0600 hours respectively. Mean duration of dialysis was 15.2 months (3-76). There were 14 hypertensive patients, defined as a basal BP > 140/90 mmHg, or those on antihypertensive medications. Taking the group as a whole a significant difference between day and night-time readings was found as regards minimal systolic BP (118 versus 107.6 mmHg), maximal systolic BP (181.6 versus 171.2 mmHg), mean diastolic BP (83.9 versus 79.6 mmHg), and maximal diastolic BP (121.7 versus 104.5 mmHg), P < 0.05. Diurnal variation, defined in the initial study as a 10% decrease of MAP occurring during any consecutive 4-h period, was present in 21 patients. In three the diurnal variation manifested as a paradoxical reduction of BP during the day. The only significant difference between those with diurnal variation and those without was the duration of dialysis, being 19.2 +/- 19.9 versus 13.3 +/- 17.3 months respectively, (P < 0.05). In a second study 18 hypertensive CAPD patients were subjected to ABPM. Nine of them had participated in the first study. These patients were specifically asked to detail their periods of sleep and arousal.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral clonidine blunts the hemodynamic responses to brief but not prolonged laryngoscopy

Study Objective: To determine whether a 300 μg dose of oral clonidine given 90 minutes prior to laryngoscopy and intubation provides hemodynamic protection from the stress of a brief (15-second) and/or a prolonged (45-second) laryngoscopy. Design: Randomized, double-blind, placebo-controlled study. Setting: Inpatients and outpatients scheduled for general anesthesia with intubation at a university-affiliated medical center. Patients: Forty patients who gave informed, written consent to receive either an oral placebo or clonidine 5 μg/kg (up to a maximum dose of 300 μg) 90 minutes prior to induction of anesthesia and to undergo either brief or prolonged laryngoscopy prior to intubation. Interventions: The patients underwent a standardized induction sequence that included d-tubocurarine 3 mg, thiopental sodium 5 mg/kg, and succinylcholine 1.5 mg/kg. The four treatment groups (each n = 10) included (1) placebo with 15-second laryngoscopy, (2) placebo with 45-second laryngoscopy, (3) clonindine with 15-second laryngoscopy, and (4) clonidine with 45-second laryngoscopy. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were mechanically obtained and recorded at 1-minute intervals for 12 minutes. Measurements and Main Results: There were no differences between groups in the premeditation hemodynamic measurements. Within each group, maximal hemodynamic variables increased significantly over the corresponding baseline values for that group. In the 15-second, but not the 45-second, laryngoscopy, clonidine successfully blunted the maximum SBP and DBP obtained when compared with the corresponding control group. In both the 15- and 45-second clonidine groups, maximum HR was significantly lower than in the corresponding placebo groups. Conclusions: Oral clonidine, when used as a preoperative medication, affords hemodynamic protection to patients undergoing a 15-second laryngoscopy. However, the stress of a 45-second laryngoscopy may be too great or the 300 μg dose of clonidine too low to provide hemodynamic protection for patients in this group.

Older age and elevated blood pressure are risk factors for intracerebral hemorrhage after thrombolysis

Intracerebral hemorrhage is an important concern after thrombolytic therapy for acute myocardial infarction, but risk factors are controversial. Accordingly, we assessed risk factors in 107 treated patients of whom 4 had intracerebral hemorrhage. Intracerebral hemorrhage occurred at a mean of 25 hours (range 3.5 to 48) after therapy and was fatal in 2 patients. Significant differences were found between patients with and without intracerebral hemorrhage for age (77 ± 7 vs 62 ± 11 years, p ≤ 0.01), and initial (161 ± 23 vs 135 ± 23 mm Hg, p ≤ 0.03) and maximal (171 ± 30 vs 146 ± 20, p ≤ 0.02) systolic blood pressures. Initial and maximal diastolic blood pressures also tended to be higher (101 ± 25 vs 86 ± 16, p ≤ 0.07; 104 ± 24 vs 90 ± 13, p ≤ 0.06). Differences did not achieve significance for comparisons of gender, height, weight, site of infarction, time to therapy, specific thrombolytic agent used, concomitant therapy, interventions and partial thromboplastin time. It is concluded that age (≥70 years) and elevated blood pressure ( ≥ 150 95 mm Hg) are important risk factors for intracerebral hemorrhage. The overall balance of benefit and risk of thrombolysis should continue to be assessed by large mortality trials.

Sustained-release verapamil as a first-step drug in the treatment of mild to moderate hypertension.

The efficacy of sustained-release verapamil as a first-stage treatment for mild to moderate, uncomplicated essential hypertension was studied. Nineteen patients aged 36-70 years (mean +/- SD 55 +/- 10 years) entered the study. Treatment with 240 mg sustained-release verapamil, once daily for 8 weeks, caused systolic and diastolic blood pressures to decline significantly during the first 2 weeks and this lower level was maintained until week 8. Heart rate decreased gradually during the treatment period reaching significance at week 8. After 2 weeks maximum systolic and diastolic blood pressures during isometric exercise were significantly reduced compared with pre-treatment values; there was no difference in the percentage increase occurring pre- and post-treatment. These measures for heart rate did not change significantly. Except for a significant reduction in cardiac index after 8 weeks left ventricular function and left ventricular mass were unchanged. The 24-h urinary Na+ excretion increased significantly after 2 and 8 weeks' treatment. Plasma renin activity, serum lipid concentrations and routine blood chemistries were not affected. Side-effects were transient and did not require discontinuation of therapy. In conclusion, sustained-release verapamil is an efficacious and well tolerated first-stage drug in the treatment of essential hypertension.

Maternal whole blood viscosity in pregnancy hypertension.

Hemoconcentration is prominent in preeclampsia. Concomitant changes in the flow properties of maternal blood, i.e. in whole blood viscosity (WBV), might be related to the occurrence of fetal or maternal complications. To test this hypothesis, WBV was estimated in 228 pregnancies. Patients were assigned to one of four groups according to maximum diastolic blood pressure. Significantly higher WBV values were found in the more hypertensive groups throughout pregnancy. WBV data, obtained between 26 and 36 weeks of amenorrhea, contributed significantly, independently of hypertension, to the prediction of fetal outcome. With regard to maternal complications, no significant contribution of WBV data could be established independently of blood pressure. The results support the hypothesis that WBV is a determining factor in the efficacy of placental perfusion.

Antithrombin III levels in preeclampsia correlate with maternal and fetal morbidity

In 57 patients with pregnancy-induced or aggravated hypertension, antithrombin III levels correlated inversely with maternal morbidity. Morbidity was determined by the maximal diastolic blood pressure, disturbance of renal and liver function, and thrombocytopenia. Antithrombin III levels and platelet counts correlated inversely with the degree of placental infarction. Proteinuria (grams per 24 hours) was most predictive of fetal outcome, which was considered to be either favorable if a healthy baby could be discharged with its mother or unfavorable in case of perinatal death or a prolonged stay in the neonatal intensive care unit. Plasma antithrombin III and serum glutamic oxaloacetic transaminase levels, in that order, augmented the number of correct predictions. Antithrombin III inhibits blood coagulation by forming irreversible complexes with activated clotting enzymes, notably with factor Xa and thrombin. Evidence is presented which suggests that antithrombin III levels in preeclampsia are depressed as a result of increased consumption in the maternal vascular tree, rather than decreased synthesis or increased urinary loss.

The Effect of Hypertension on Fetal Growth

To assess the effect of hypertension on fetal growth we studied all hypertensive patients who delivered at the University Hospital “Wilhelmina Gasthuis”, Amsterdam, over a five-year period. They were studied on a retrospective basis. Patients were excluded from this study if they had a multiple pregnancy or a hydatidiform mole. Out of 7454 women who delivered after 28 weeks gestation between 1975 and 1981, 716 nulliparae (N.P.) and 489 multiparae (M.P.) had a diastolic bloodpressure of ≥ 90 mm on at least two occasions. They were matched for age and parity with a normotensive control group, who delivered at our University Hospital in the same period. The Small-for-Gestational-Age (SGA) infant was designated as one whose birthweight fell below 5th percentile. Only the maximum diastolic bloodpressure level proved to have an association with the incidence of SGA infants. The influence of proteinuria appeared to be of minor importance with respect to fetal growth retardation when maximum diastolic bloodpressu...

The Effect of Hypertension on Fetal Growth

To assess the effect of hypertension on fetal growth we studied all hypertensive patients who delivered at the University Hospital “Wilhelmina Gasthuis”, Amsterdam, over a five-year period. They were studied on a retrospective basis. Patients were excluded from this study if they had a multiple pregnancy or a hydatidiform mole. Out of 7454 women who delivered after 28 weeks gestation between 1975 and 1981, 716 nulliparae (N.P.) and 489 multiparae (M.P.) had a diastolic bloodpressure of ≥ 90 mm on at least two occasions. They were matched for age and parity with a normotensive control group, who delivered at our University Hospital in the same period. The Small-for-Gestational-Age (SGA) infant was designated as one whose birthweight fell below 5th percentile. Only the maximum diastolic bloodpressure level proved to have an association with the incidence of SGA infants. The influence of proteinuria appeared to be of minor importance with respect to fetal growth retardation when maximum diastolic bloodpressu...

Hypertension-Hypotension in Pregnancy

Data from 38,636 pregnant women were studied to determine the best criteria for diagnosing pregnancy hypertension based on the constellation of clinical factors yielding poorest perinatal and long-term results to the offspring. It was found that the combination of maximum diastolic blood pressure and maximum proteinuria, as observed during the interval 28 weeks to term, provided the closest correlation with outcome. This information offered an objective means for establishing a classification of hypertension-hypotension in late pregnancy.

Cardiac responses to stimulation of thoracic afferents in the primate and canine.

Excitatory cardiovascular responses to electrically stimulated upper thoracic sympathetic afferent nerves were observed in halothane-anesthetized mongrel dogs and monkeys. The central end of the transected ventral limb of the left ansa subclavia was stimulated before and after several types of denervation. Significant increases in right and left ventricular maximum systolic pressures, systolic and diastolic systemic blood pressures, and aortic flow were observed. The carotid sinuses were denervated bilaterally and stimulation of the ansa was repeated. The cardiovascular responses to stimulation of the ventral ansa after carotid sinus denervation were greater in magnitude than those observed prior to denervation. This carotid sinus modulation of cardiovascular responses was observed in dogs and monkeys. Cardiovascular responses to stimulation of the ventral ansa after bilateral vagotomy were significantly less than the responses observed after carotid sinus denervation prior to vagotomy. However, the responses after vagotomy were statistically identical to responses obtained while stimulating the ventral ansa when the carotid sinuses and vagi remained intact.