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C Canali

Publications and source records attributed to C Canali.

At least 19 recordsLinked to original sources
PubMed2006

Search for laser-induced formation of antihydrogen atoms.

Antihydrogen can be synthesized by mixing antiprotons and positrons in a Penning trap environment. Here an experiment to stimulate the formation of antihydrogen in the n = 11 quantum state by the introduction of light from a CO2 continuous wave laser is described. An overall upper limit of 0.8% with 90% C.L. on the laser-induced enhancement of the recombination has been found. This result strongly suggests that radiative recombination contributes negligibly to the antihydrogen formed in the experimental conditions used by the ATHENA Collaboration.

Journal Article↗
PubMed2006

The BNP assay does not identify mild left ventricular diastolic dysfunction in asymptomatic diabetic patients.

AIMS: We examined the usefulness of BNP for screening for left ventricular (LV) diastolic dysfunction in a sample of type 2 diabetic patients, without structural heart disorder, who have never presented symptoms or signs of heart failure (HF). METHODS AND RESULTS: Seventy-six consecutive patients admitted to the Outpatient Diabetes Clinic were studied. Blood samples were analyzed using the Triage BNP fluorescence immunoassay (Biosite Diagnostics, La Jolla, CA, USA). Echocardiography examinations were performed, with no knowledge of the BNP value. A total of 39 patients out of 76 (51%) were diagnosed with LV diastolic dysfunction and 23 (30%) with LV hypertrophy. Of the patients with LV diastolic dysfunction, impaired relaxation and pseudonormal pattern accounted for 97 and 3% of the cases, respectively. BNP levels among subjects with LV diastolic dysfunction (26+/-22 pg/ml, n=39) were not significantly different from patients with normal LV function (24+/-23 pg/ml, n=37 pg/ml; Mann-Whitney U-test, Z=-0.4, n.s.). CONCLUSIONS: Our data confirm alarmingly high prevalence of LV diastolic dysfunction in asymptomatic individuals with diabetes. Identification of patients with preclinical diabetic cardiomyopathy should be a research and clinical priority. BNP levels cannot be used to detect mild LV diastolic dysfunction in this subset of patients, which requires Doppler echocardiography to be detected.

Aged↗
PubMed2005

New source of dense, cryogenic positron plasmas.

We have developed a new method, based on the ballistic transfer of preaccumulated plasmas, to obtain large and dense positron plasmas in a cryogenic environment. The method involves transferring plasmas emanating from a region with a low magnetic field (0.14 T) and relatively high pressure (10(-9) mbar) into a 15 K Penning-Malmberg trap immersed in a 3 T magnetic field with a base pressure better than 10(-13) mbar. The achieved positron accumulation rate in the high field cryogenic trap is more than one and a half orders of magnitude higher than the previous most efficient UHV compatible scheme. Subsequent stacking resulted in a plasma containing more than 1.2 x 10(9) positrons, which is a factor 4 higher than previously reported. Using a rotating wall electric field, plasmas containing about 20 x 10(6) positrons were compressed to a density of 2.6 x 10(10) cm(-3). This is a factor of 6 improvement over earlier measurements.

Journal Article↗
PubMed1999

Effects of induced endometritis on the life-span of corpora lutea in pseudopregnant rabbits and incidence of spontaneous uterine infections related to fertility of breeding does.

A significant percentage of rabbit does fail to become pregnant after AI. We hypothesized that uterine infections induced by the insemination procedure are related to delayed luteolysis and high progesterone concentrations noted to present at the time of AI. The rabbits, randomly assigned to 4 groups (3 animals/group), were given 0.8 microgram GnRH analogue (Day 0) just prior to infusing the uterus with sterile extender (control group) or with extender inoculated with 0.5, 1, and 2 x 10(6) Pasteurella multocida (treated groups). The effects of treatments on functional life-span of CL were assessed by evaluating plasma progesterone from Day 0 to Day 23 of pseudopregnancy. In treated rabbits, the progesterone profiles closely overlapped those found in controls until approximately Day 14. Thereafter, they varied greatly between animals, but luteolysis was delayed by at least 5-6 d and developed less rapidly than in controls. On Day 21, progesterone concentrations were higher than normal in 4 treated does. In a field survey, vaginal swabs were collected at the time of the second AI from 114 non-pregnant rabbits and those positive to bacteriological culture, were killed humanely 16 d later to collect uterine swabs. Positive uterine swabs were found only in 19 of the 34 does having a positive vaginal swabs and all of them were not pregnant. The most frequent pathogen isolated was S. aureus (50%), followed by E. coli (37.5%) and P. multocida (12.5%). We demonstrated that uterine infection increases the life-span of CL in non-pregnant does and that infections of the genital tract system are quite common among does on breeding farms, probably related to using AI.

Animals↗
PubMed1999

Nitric oxide synthase acutely regulates progesterone production by in vitro cultured rabbit corpora lutea.

We examined the presence and the regulation of nitric oxide (NO) synthase (NOS) using in vitro cultured corpora lutea (CL) obtained from rabbits at days 4 and 9 of pseudopregnancy. The role of NO and NOS on steroidogenesis was also investigated using the same CL preparations after short-term incubations (30 min and 2 h) with the NO donor, sodium nitroprusside (NP), the NOS inhibitor, Nomega-nitro-l-arginine methyl ester (l-NAME) and prostaglandin (PG) F-2alpha. The basal NOS activity was greater in CL at day 4 than at day 9, and was also differently modulated by PGF-2alpha, depending on the age of the CL. The addition of PGF-2alpha to day 4 CL had no effect, but PGF-2alpha on day 9 caused a threefold increase in NOS activity. NP caused a two- to fivefold decrease in release of progesterone from CL of both ages, and this inhibitory effect on steroidogenesis was reversed by l-NAME. All treatments failed to modify basal androgens and 17beta-oestradiol was not detectable in either control or treated CL. These results suggest that NO is effectively involved in the regulation process of steroidogenesis, independently of 17beta-oestradiol. PGF-2alpha had no effect on day 4, but induced luteolysis on day 9, by reducing progesterone (P</=0. 01) to about 18% of control. The luteolytic action of PGF-2alpha was completely reversed by co-incubation with l-NAME, thus supporting the hypothesis that luteolysis is mediated by NO. The addition of NP or l-NAME did not modify the in vitro release of PGF-2alpha. We hypothesised that PGF-2alpha upregulates NOS activity and, consequently, the production of NO, which acutely inhibits progesterone release from day 9 CL of pseudopregnant rabbits.

Analysis of Variance↗
PubMed1998

Changes in refractoriness of rabbit corpora lutea to a prostaglandin F2 alpha analogue, alfaprostol, during pseudopregnancy.

The responsiveness of rabbit corpus luteum to 200 micrograms of the prostaglandin F2 alpha (PGF2 alpha) analogue, alfaprostol, between Days 3 and 9 of pseudopregnancy was assessed by evaluating the decline in plasma progesterone after treatment with PGF2 alpha in 81 New Zealand White (NZW) rabbits. On Days 3-5, functional luteolysis was not observed. On Days 6, 7, and 8 of pseudopregnancy, the number of rabbits responsive to PGF2 alpha, rose from 38% to 71% and 83%, respectively. In the other cases, the effect of the PGF2 alpha analogue was transient as CL recovered in the following 2 or 3 days. By contrast, on Day 9 luteolysis was effective and persistent in all the animals. In rabbits treated on Day 9, progesterone decreased gradually from 10.6 +/- 0.7 within the first 6 h, but fell to 3.6 +/- 1.5 ng/mL (p < 0.01) 12 h after PGF2 alpha and to 0.2 +/- 0.1 ng/mL (p < 0.01) 24 h later.

Animals↗
PubMed1998

Structural abnormalities and not diastolic dysfunction are the earliest left ventricular changes in hypertension. HARVEST Study Group.

It has been claimed that diastolic dysfunction is the earliest cardiac abnormality in hypertension, preceding the development of left ventricular (LV) structural abnormalities. To detect early signs of hypertensive cardiac involvement 722 subjects (533 men and 189 women), 18-45 years old, with stage I hypertension, were studied by M-mode and Doppler echocardiography. Blood pressure was measured by 24-h ambulatory monitoring. Ninety-five normotensive individuals of similar age and gender distributions were studied as controls. Significant, though modest, changes of LV mass and geometry were found in the participants in comparison with the normotensive controls. The increment was +10.4 g/m2 for LV mass index, +1.8 mm for LV wall thickness, and +0.032 for relative wall thickness. A slight increase in atrial filling peak velocity was found in the hypertensive subjects at Doppler analysis of transmitral flow, but the ratio of early to atrial velocity of LV diastolic filling did not differ between the two groups. In multiple regression analyses, which included age, body mass index, heart rate, smoking, and physical activity, 24-h mean blood pressure emerged as a significant predictor of LV mass index (men, P = .003; women, P = .04) and wall thickness (men, P = .03; women, P = .004) in the hypertensive subjects, whereas no index of diastolic filling was significantly associated with ambulatory blood pressure in either gender. The present data indicate that changes in LV anatomy are the earliest signs of hypertensive cardiac involvement. Left ventricular filling is affected only marginally in the initial phase of hypertension.

Adolescent↗
PubMed1997

Remodeling of the left ventricle in primary aldosteronism due to Conn's adenoma.

BACKGROUND: Since hyperaldosteronism has been experimentally related to myocardial interstitial fibrosis, we investigated the effects of hypertension and excess aldosterone due to aldosterone-producing adenomas (APAs) on the heart. METHODS AND RESULTS: In 52 hypertensive individuals, we performed Doppler echocardiography for estimation of left ventricular (LV) wall thickness and dimensions, transmitral LV filling flow velocity indexes, and 24-hour ambulatory blood pressure monitoring. Consecutive patients with APAs (n = 26) and essential hypertension (EH, n = 26) were individually matched for age, sex, race, body mass index, casual blood pressure, and known duration of hypertension. The matched groups were similar for demography, casual and 24-hour blood pressure values and variability, and duration of hypertension but differed for serum potassium, plasma renin activity, and aldosterone levels (all P < .001). A thicker interventricular septum (P = .015) and posterior wall (P = .009) and a higher LV mass index (118 +/- 5 versus 100 +/- 4 g/m2, P = .009) were observed in APA compared with EH patients. Both septum and posterior wall thicknesses had a significant direct relationship with age, plasma aldosterone, and mean blood pressure. The integral of the early diastolic filling wave (Ei) (P = .011) and the ratio Ei/Ai (A wave integral) (P = .038) were lower and the atrial contribution to LV filling was higher (52 +/- 2% versus 46 +/- 2%, P = .038) in APA than in EH patients. The ratio Ei/Ai was significantly (P = .008) inversely related only to age and plasma aldosterone. CONCLUSIONS: In APA patients, the excess aldosterone is associated with both increased LV wall thickness and mass and decreased early diastolic LV filling indexes compared with demographically similar EH with superimposable blood pressure values, profile, and variability.

Adenoma↗
PubMed1997

Interactive action of the white-coat effect and the blood pressure levels on cardiovascular complications in hypertension.

PURPOSE: This study was undertaken to investigate whether there is a relationship between the white-coat effect and the cardiovascular complications of hypertension. PATIENTS AND METHODS: In 1,013 consecutive borderline to severe hypertensive outpatients (889 men) with a mean age (+/-SE) of 33.6 +/- 0.5 years and a mean office blood pressure of 152.3 +/- 0.6/95.5 +/- 0.4 mm Hg, blood pressure was measured by noninvasive 24-hour ambulatory monitoring. Target organ damage was assessed by electrocardiogram, chest X-ray, echocardiography, and ophthalmoscopy. The degree of target organ damage and of left ventricular hypertrophy was assessed in the subjects divided according to the levels of their daytime blood pressure and the extent of their white-coat effect. RESULTS: The subjects with a high white-coat effect showed a greater degree of hypertensive complications than those with intermediate or a low white-coat effect. The significant association between the white-coat phenomenon and the hypertensive complications was confirmed by the results of stepwise regression analyses, where sex, age, duration of hypertension, and ambulatory blood pressure were added to the model. A two-way ANOVA showed that both ambulatory blood pressure and the white-coat effect were related to the degree of target organ damage and to left ventricular hypertrophy. Moreover, daytime blood pressure and the white-coat effect showed an interactive effect on hypertensive complications, as the influence of the white-coat effect on end organs increased with increasing levels of ambulatory blood pressure. CONCLUSIONS: The present results show that the white-coat effect is related to the degree of hypertensive complications and that this association is stronger in the subject with more severe hypertension.

Adult↗
PubMed1997

Does orthostatic testing have any role in the evaluation of the young subject with mild hypertension?: an insight from the HARVEST study.

The aim of the study was to assess the clinical significance of the blood pressure (BP) reaction to standing in 1029 stage I hypertensives. Office BP was measured six times in the supine position and six times after 2 min of standing. All subjects underwent 24-h ambulatory BP monitoring, and measurements of 24-h urinary epinephrine and norepinephrine excretion. Echocardiography was performed in 636 patients. With use of mixture analysis we could single out a population with abnormal diastolic BP response to standing (hyperreactors, n = 95). These subjects had a diastolic BP increase from lying to standing of >11 mm Hg. The other subjects were defined as normoreactors (n = 934). Office systolic BP was similar in the two groups. Diastolic BP was lower (91 +/- 6 mm Hg v 95 +/- 5 mm Hg, P < .0001) and heart rate was higher in the hyperreactors (77 +/- 10 beats/min v 75 +/- 9 beats/min, P = .004). After adjusting for age, gender, and smoking habits the statistical significance did not change. Adjusted 24-h systolic BP (P = .02) and diastolic BP (P = .02) were higher in the hyperreactors than in the normoreactors. Hyperreactors were characterized by higher cardiac index (3.2 +/- 0.8 L/min/m2 v 3.0 +/- 0.7 L/min/m2, P = .008 for adjusted values), lower total peripheral resistance (1420 +/- 330 dyne/sec/cm(-5) v 1600 +/- 380 dyne/sec/cm(-5), P = .003), and higher urinary norepinephrine output (114.9 +/- 80.3 microg/24 h v 90.6 +/- 78.5 microg/24 h, P = .03). Dimensional echocardiographic data and albumin excretion rate did not differ between the two groups. In conclusion, mixture analysis allowed us to identify a population of young mild hypertensives with exaggerated BP response to standing. Hyperreactors were characterized by higher whole-day BP and by a hyperkinetic hemodynamic pattern as a result of increased sympathetic tone.

Adolescent↗
PubMed1997

Target organ damage and ambulatory blood pressure in stage I hypertension. The Hypertension and Ambulatory Recording Venetia Study.

According to recent international guidelines the decision on whether to treat young subjects during the early phase of hypertension should be based not only on their office blood pressure but also on their ambulatory blood pressure and whether target organ damage has occurred. Few data on the prevalence of hypertensive complications in young subjects with mild hypertension are available. In the Hypertension and Ambulatory Recording Venetia Study (HARVEST), a multicenter trial conducted in northeast Italy, the percentage of young borderline-to-mild hypertensive subjects with echocardiographic left ventricular hypertrophy was 4.5% and the percentage with concentric remodeling was 4%. Clear differences in cardiac size and geometric adjustment to ambulatory systolic pressure between the two sexes were found. The impact of blood pressure on the walls of the left ventricle and on the left ventricular mass was remarkable in women but weak in men. The assessment of left ventricular systolic function confirmed that many young mild hypertensive subjects have an increased ejective performance. The left ventricular contractility evaluated by midwall measurement was, however, found to be depressed in 9.2% of the HARVEST participants. Their left ventricular diastolic function was similar to that of 50 normotensive controls. The prevalence of microalbuminuria [albumin excretion rate (AER) > 30 mg/24 h) was 6.1%, only slightly higher than that found by other authors among normotensive subjects and much lower than that observed among patients with more severe hypertension. For our stage I hypertensives, however, the AER was correlated to the 24 h blood pressure with high statistical significance, whereas we found no relationship between the AER and left ventricular mass index either for all of the subjects taken together or for the men and women considered separately. The results suggest that renal and cardiac involvement do not occur in parallel during the initial phase of hypertension.

Journal Article↗
PubMed1997

Ambulatory blood pressure monitoring editing criteria: is standardization needed? Hypertension and Ambulatory Recording Venetia Study (HARVEST) Group, Italy.

The effect of different editing methods on the reproducibility of ambulatory blood pressure and on its correlation with microalbuminuria was studied in a population of 584 stage I hypertensives participating in the Hypertension and Ambulatory Recording Venetia Study (HARVEST) Group. For systolic blood pressure (SBP), a modified version of the Casadei method showed the best reproducibility indices, followed by the original Casadei and the Kennedy methods. The Staessen, SpaceLabs, and A&D methods showed poorer indices, irrespective of whether calculations were made in recordings with more or less than 10% artifactual readings. For diastolic blood pressure (DBP), reproducibility indices did not substantially vary with the various editing procedures except for the Kennedy method, which showed a slightly better performance. Blood pressure variability (standard deviation) showed a better reproducibility with the original and modified versions of the Casadei and the Kennedy procedures than with the other methods, especially in the subjects with percentage of measurement errors greater than 10%. The correlation coefficients between 24-h SBP and albumin excretion rate ranged from 0.128 for the raw data to 0.154 for the data edited according to the Casadei procedures. For DBP, the correlation coefficients were similar except for DBP edited with the Kennedy method, which did not correlate with albumin excretion rate to a statistically significant level. These data suggest that, to make the results of different laboratories comparable, common ambulatory blood pressure editing criteria should be used. The modified version of the Casadei procedure, which is automatic and can be applied to recordings obtained from any device, should be regarded as the method of choice.

Adolescent↗
PubMed1996

Relationship of plasma renin activity with caffeine intake and physical training in mild hypertensive men. HARVEST Study Group.

UNLABELLED: To study the relationship between plasma renin activity (PRA) and coffee consumption, cigarette smoking, alcohol intake and physical activity habits. SETTING: The multicentre HARVEST trial, involving 17 Hospital Centres in Northeast Italy. SUBJECTS: 351 borderline to mild hypertensive men (mean age +/- SEM 22.7 +/- 0.47 years), never treated for hypertension. INTERVENTIONS: Office and 24-hour blood pressure measurement, supine and standing PRA levels, and urinary catecholamines output. MAIN OUTCOME MEASURES: PRA levels according to coffee intake and physical activity status. RESULTS: Coffee intake showed a major effect on PRA. Supine PRA levels were 40% higher in the subjects abstaining from coffee (n = 94) than in the coffee drinkers and was similar in the moderate (n = 223) and heavy (n = 34) drinkers. A weaker negative association was found between coffee use and PRA on standing. Office and whole-day blood pressure and heart rate, and urinary catecholamines did not differ according to coffee intake. Supine PRA was lower in the subjects performing regular physical activity than in the inactive subjects. Office and whole-day diastolic blood pressure and heart rate, and urinary norepinephrine were lower in the active than in the sedentary men. No relationship was found between PRA measured either in the supine or the upright posture and tobacco or alcohol use. In a multiple linear regression model supine PRA was negatively correlated with age, coffee consumption and physical activity habits. CONCLUSIONS: Chronic coffee intake and physical training showed an inverse relationship with PRA in mild hypertensive men, while tobacco and alcohol use were unrelated to PRA.

Adolescent↗
PubMed1996

Supernormal left ventricular performance in young subjects with mild hypertension: an alerting response to the echocardiographic procedure?

1. To assess the clinical significance of supernormal left ventricular systolic function in the initial phase of hypertension, 635 never-treated 18-45-year-old borderline to mild hypertensive subjects (477 males, 158 females) were studied. All subjects underwent echocardiography, 24 h ambulatory blood pressure monitoring and 24 h urine collection for catecholamine dosage. 2. Subjects whose left ventricular shortening-stress relationship was above the 95% confidence intervals of 50 normotensive subjects of similar age and sex distribution were defined as having supernormal function. 3. Age, duration of hypertension and left ventricular mass were similar in the hypertensive subjects with normal (85%) and supernormal (15%) ejective performance. Subjects with supernormal function showed higher office systolic blood pressure (P < 0001), office heart rate (P = 0.03) and cardiac index (P < 0001). Conversely, 24 h systolic blood pressure, 24 h heart rate and 24 h catecholamine output did not differ according to left ventricular function. 4. In conclusion, the greater white-coat effect and the normal baseline sympathetic tone exhibited by the patients with increased performance suggest that supernormal left ventricular pump function is only a marker of the alerting reaction elicited by the echocardiographic examination.

Adult↗
PubMed1996

Changes in left ventricular anatomy and function in hypertension and primary aldosteronism.

We investigated the effects on the heart of hypertension due to the excess of aldosterone and suppression of the renin-angiotensin system caused by primary aldosteronism with M-mode echocardiography and transmitral Doppler flow velocity measurements. We studied 34 consecutive patients with primary aldosteronism and 34 with essential hypertension individually matched for age, gender, race, body mass index, blood pressure values, and duration of hypertension. The groups were similar in age, body mass index, blood pressure, and duration of hypertension. However, lower serum potassium levels (3.5 +/- 0.6 versus 4.1 +/- 0.2 mmol/L, P < .0001) and plasma renin activity (0.53 +/- 0.45 versus 1.82 +/- 1.59 ng Ang I x mL-1 x h-1, P < .0001) and higher plasma aldosterone levels (1107 +/- 774 versus 206 +/- 99 pmol/L, P < .0001), left ventricular wall thickness, and left ventricular mass index (112 +/- 4.7 versus 98 +/- 3.7 g/m2, P = .029) were found in patients with primary aldosteronism compared with those with essential hypertension. Similarly, the PQ interval was longer (173 +/- 20 versus 141 +/- 14 milliseconds, P < .001) in primary aldosteronism than in essential hypertension patients. Significantly more primary aldosteronism than essential hypertension patients had left ventricular hypertrophy or left ventricular concentric remodeling (50% versus 15%, chi 2 = 11.97, P = .007). Both the E wave flow velocity integral (1063 +/- 65 versus 1323 +/- 78, P = .013) and the E/A integral ratio (0.91 +/- 0.05 versus 1.25 +/- 0.08, P < .001) were lower, and atrial contribution to left ventricular filling was higher (53.3 +/- 1.5% versus 45.5 +/- 1.3% P < .001) in patients with primary aldosteronism compared with essential hypertension patients. After 1 year of follow-up, highly significant decreases of left ventricular wall thickness and mass were observed in patients treated with surgical excision of an aldosterone-producing tumor, but not in those with medical therapy. Thus, in patients with primary aldosteronism, the excess aldosterone with suppression of the renin-angiotensin system is associated with both increased left ventricular mass and significant changes of left ventricular diastolic filling. The former changes appear to be reversible on removal of the cause of excessive aldosterone production.

Adult↗
PubMed1996

Relation of 24-hour ambulatory blood pressure and short-term blood pressure variability to seasonal changes in environmental temperature in stage I hypertensive subjects. Results of the Harvest Trial.

We investigated the seasonal changes in blood pressure (BP) and in short-term BP variability determined using ambulatory blood pressure monitoring (ABPM). 1000 white subjects, who took part in the multicenter HARVEST study, underwent ABPM with the A&D TM-2420 or the Spacelabs 90207. Standard deviation of the mean daytime and nighttime BP was taken as an index of short-term BP variability (v). Maximal outdoor temperature (Tmax) during each ABPM was obtained from local Meteorological Centers. Subjects were divided according to season and to quartiles of Tmax. A subgroup of 46 persons who repeated ABPM in Winter and Summer was also studied. We observed evident seasonal differences in office and ambulatory systolic BP (SBP) with a peak during Winter. Diastolic BP (DBP) and heart rate did not vary throughout the four seasons. Office SBP (p < 0.01), 24-hour (p < 0.002), daytime SBP (p < 0.0001), both daytime SBPv (p < 0.0001), DBPv (p < 0.02), and nighttime SBPv (p < 0.05), DBPv (p < 0.02) as well as norepinephrine (p < 0.005) were significantly higher during Winter than Summer. Similar differences were observed in subjects grouped in quartiles of Tmax. In the subgroup daytime but not nighttime SBP was higher in the cold season. Average 24-hour SBP (p < 0.05), daytime SBP (p < 0.02), daytime SBPv (p < 0.001) and DBPv (p < 0.05) and norepinephrine (p < 0.0001) were significantly negatively correlated with Tmax in the whole population. BP is higher and subjected to wider oscillations during the cold season in patients with mild hypertension probably due to sympathetic activation. The assessment of a hypertensive subject may give different results according to the season.

Adolescent↗
PubMed1996

24 h rhythm of blood pressure and forearm peripheral resistance in normotensive and hypertensive subjects confined to bed.

OBJECTIVES: To define whether a diurnal rhythm of peripheral resistance exists in normotensive and hypertensive subjects, has any relationship with that of blood pressure and differs in dipper and non-dipper hypertensives. DESIGN AND METHODS: Forty-three subjects (13 normotensives and 30 mild-to-moderate essential hypertensives) confined for 24 h to bed were included. Blood pressure was recorded for 22 h at 15 min intervals, plethysmographic forearm flow was simultaneously measured and forearm resistance calculated. The analysis was performed for the whole 22 h period and for three 4 h truncated periods, two of certain wakefulness and one of certain sleep. RESULTS: A circadian rhythm of forearm resistance was shown in the normotensives, paralleling that of blood pressure. All the normotensives were dippers, with a nocturnal blood pressure dip (systolic/diastolic) of -4.5/-6.0%. In the hypertensives, the day/night blood pressure trends were not homogeneous: 21 showed higher blood pressure values during waking time, with a trend quite similar to that of the normotensives, whereas the other nine were non-dippers. Resistance was lower during sleep than during waking both in the normotensives and in the dipper hypertensives, whereas in the non-dippers it was higher during sleep. CONCLUSIONS: A sleep/waking rhythm of peripheral resistance with the highest values during daytime and the lowest during night-time does exist in normotensive as well as in the majority of hypertensive subjects resting continuously in bed, and therefore is largely independent of physical activity. Only in a minority of hypertensive patients are higher values of peripheral resistance present during sleep.

Adult↗