Role of central serotonergic (5-HT2) receptor in blood pressure regulation in rats

To investigate the role of the serotonergic nervous system in blood pressure regulation, 5 micrograms of 5-hydroxytryptamine (5-HT) was given i.c.v. before and after 1 microgram of i.c.v. xylamidine or 200 micrograms of i.c.v. ketanserin or 200 micrograms of i.v. ketanserin in conscious Wistar Kyoto rats. Also i.v. (0.5, 1, 2 micrograms) or i.c.v. (1 microgram) phenylephrine (PHE) were given before and after 1 microgram of i.c.v. xylamidine. I.c.v. 5-HT elicited a consistent pressor response of approximately 27mmHg and slight decrease in heart rate. MAP and heart rate did not change after xylamidine or ketanserin. Whereas pressor response to i.c.v. 5-HT after i.c.v. ketanserin or i.c.v. xylamidine was suppressed, it did not change after i.v. ketanserin. Neither i.c.v. nor i.v. PHE-induced pressor response was influenced by i.c.v. xylamidine pretreatment. These data suggest that the central 5-HT2 receptor may subserve pressor function in rats.

Randomized double-blind trial of intracoronary urokinase for acute myocardial infarction: multicenter study

The efficacy of intracoronary urokinase (UK) in an acute myocardial infarction has not been firmly established in a randomized fashion. Two hundred and ten patients were randomized to UK therapy (107 patients) and placebo (103 patients). Successful recanalization was achieved in 74% of the UK group vs 17% in the placebo group (p less than 0.01). The success rate was dose dependent up to 960,000 I.U. Clinical course was favorable and left ventricular enddiastolic pressure was reduced significantly in the UK group compared with the placebo group (p less than 0.05). Ejection fraction one month after the study was better in the reopened group than in the occluded group. Thus, early administration of UK can establish coronary reflow in a high proportion of patients and appears to favor the clinical course.

Comparison of effects of vegetable protein diet and animal protein diet on the initiation of anemia during vigorous physical training (sports anemia) in dogs and rats

The effect of the quality of dietary protein on the initiation of temporary anemia during vigorous physical training (sports anemia) was studied in dogs and rats. In the dog experiment, one group of dogs was fed a crude animal protein (AP) diet and the other a crude vegetable protein (VP) diet. After 6 weeks on the diets in a sedentary state (rest period), all the dogs were forced to run every day for two weeks (exercise period). The rat experiment was carried out using purified nutrient mixtures. Casein (C) was used as AP and gluten (G) as VP. Feeding was done for two weeks in two series with two diet groups of rats. One series was 15% protein feeding (15% C and 15% G) groups and the other 24% protein feeding (24% C and 24% G) groups. In each group, one group remained in a sedentary state (rest group), and the other ran vigorously on a treadmill every day for one week (exercise group). In a sedentary state, there was a slight tendency for the hemoglobin content or erythrocyte count to be reduced, even when the values remained within the normal range, in dogs and rats fed VP. On the other hand, after vigorous running, significant anemia (reduction of hemoglobin) appeared in the VP diet dogs and in all exercise rat groups except the 24% C group. It was confirmed that the anemia was caused by a reduction of erythrocyte resistance to hemolysis, which was closely related to changes in the lipid composition of blood (serum and especially erythrocytes). The change in lipid profile revealed by the experiments was a reduction of free cholesterol in blood associated with an increase of lysolecithin in dogs during the exercise period and in the rat exercise groups. It was suggested that repeated physical exercise increased the activity of LCAT (lecithin-cholesterol-acyltransferase) in the liver, spleen, etc., resulting in the above changes in lipid patterns in the blood. In dogs of AP and rats of 24% C, however, those changes in lipid pattern caused by exercise and sports anemia did not appear significantly. The different effects of the AP diet seemed to be due to the antagonistic effects of lysine, which was present in sufficient amounts in the diet. Thus the theoretical basis for our recommendation of a high amount of AP in the diet to prevent sports anemia was clarified by the present experiments.(ABSTRACT TRUNCATED AT 400 WORDS)

Post-reperfusion function evaluated using two-dimensional echocardiography in dog: systolic/diastolic function vs percent necrosis

Two-dimensional echocardiography (2DE) was performed in nine dogs with three hour proximal occlusion of the left anterior descending coronary artery and seven day reperfusion for sequentially mapping systolic functions (Seg-FAC%: percent segmental fractional area change) and diastolic functions (Seg-VLAC: mean velocity of segmental luminal area change) of eight segments in a mid-papillary left ventricular short-axis cross-section. The corresponding segment functions on 2DE to the most profoundly affected segment were evaluated by triphenyl-tetrazolium-chloride staining seven days post reperfusion, and categorized in two groups in terms percent mural necrosis (N%): N% greater than or equal to 40% in group A and N% less than 40% in group B, respectively. Seg-FAC% showed a significant difference between the two groups seven days post reperfusion (13.4 +/- 9.4% in group A, 53.3 +/- 7.7% in group B), while Seg-VLAC showed significant differences in the groups at three hours post occlusion (-1.6 +/- 2.1 cm2/sec in group A and 3.2 +/- 2.6 cm2/sec in group B) and seven days post reperfusion (0.48 +/- 4.7 cm2/sec in group A and 7.5 +/- 2.4 cm2/sec in group B). At seven days post reperfusion, Seg-VLAC correlated negatively with N% (r = -0.94), while Seg-FAC% did not with N% (r = -0.58). It was concluded that Seg-VLAC, after three hours' occlusion, predicts the recovery of the regional left ventricular function seven days after reperfusion; and Seg-VLAC, seven days after reperfusion can estimate the regional transmurality of necrosis thereafter.

[The role of the sympathetic nervous system and adrenals in hemodynamic changes after intracerebroventricular administration of 5-hydroxytryptamine in rats]

Recently, the role of the serotonergic nervous system has been implicated in blood pressure regulation and in the pathogenesis of hypertension. However, the effects of 5-hydroxytryptamine (5-HT) administration on hemodynamics have been notoriously inconsistent and the precise mechanism of the blood pressure regulation of the serotonergic nervous system has not been elucidated yet. In our previous study, we demonstrated that the intracerebroventricular (i.c.v.) administration of 5-HT in rats elicited consistent pressor response with concomitant increase in plasma norepinephrine and that the pressor response was abolished by systemic pretreatment of phenoxybenzamine or by serotonin receptor antagonist, methysergide. The purpose of this experiment is to investigate further the relationship between the sympathetic nervous system and the serotonergic nervous system.

[Effects of intracerebroventricular (I.C.V.) administration of 5-hydroxytryptamine (5-HT) on hemodynamics in conscious spontaneously hypertensive rats (SHR): relation to sympathetic nervous system]

Recently, the serotonergic nervous system has been receiving attention as part of the blood pressure regulating mechanism of the central nervous system, and it has been postulated that the system may participate in the pathogenesis of hypertension. The purpose of this experiment is to investigate the mechanism of hemodynamic change after i.c.v. administration of 5-HT in SHR and in normotensive Wistar Rats (WR).

MATERIALS AND METHODS

Twenty-week-old male SHR (n = 11) and age-matched WR (n = 14) were used. On the day before the experiments, the unilateral carotid artery and jugular vein were cannulated. Also, a cannula was inserted stereotaxically into the anterior horn of the lateral cerebral ventricle. Experiments were performed under the conscious and minimum restrained state. Experiment I: After observation of resting mean arterial pressure (MAP) and heart rate (HR) for 20 minutes, 5-HT (5 micrograms/5 microliter saline) was administrated i.c.v., and MAP and HR were observed for 90 minutes. Then, 200 micrograms of phenoxybenzamine (POB) was given from the jugular cannula. Thirty minutes after the POB administration when MAP was stabilized, 5 micrograms of 5-HT was again given i.c.v., and MAP and HR were recorded for 30 minutes. Experiment II: Plasma norepinephrine (PNE) was measured before and 2 minutes after 5-HT i.c.v. administration. The control sample (1.5 ml) was withdrawn at least 30 minutes before the 5-HT injection, and immediately after the blood sampling, the same amount of blood which was obtained from the age-matched donor rat of the same strain was transfused.

RESULTS

Experiment I: Resting MAP was 136.4 +/- 5.1 mmHg in SHR and 99.1 +/- 3.0 mmHg in WR. I.c.v. administration of 5-HT elicited consistent pressor response in SHR and in WR.(ABSTRACT TRUNCATED AT 250 WORDS)

Utilization of urea nitrogen in Papua New Guinea highlanders

The utilization of urea nitrogen was examined in 10 healthy adult men from a village near Lufa, in the Eastern Highlands Province of Papua New Guinea. The staple diet of these men was sweet potatoes. [15N]urea was used as tracer for urea released into their intestinal tracts and the utilization of the urea-N was estimated from the trend of 15N. The men were orally given [15N]urea at the beginning of the study and then their daily protein intake, serum protein levels, 15N excretion in the feces and urine, 15N retention in the whole body and 15N incorporation into serum protein were examined. Their daily protein intake (32.2 +/- 8.6 g/day) was low, but their serum protein level (8.05 +/- 0.41 g/100 ml) was within the normal range. 15N retention in the whole body on day 3 was estimated to be 35.4 +/- 20.2% of the total amount administered, calculated from the recoveries in the feces (1.64 +/- 0.85%) and urine (63.0 +/- 20.5%) on days 1-3. The utilization of urea nitrogen in Papua New Guinea highlanders was confirmed from the finding of 15N incorporation into serum proteins on day 3 (0.008 +/- 0.005 atom% excess). This incorporation was negatively correlated with the urinary nitrogen excretion and serum protein level. This correlation suggests that Papua New Guinea highlanders with low urinary nitrogen excretion or a low level in serum protein, who are in a poor state of protein nutrition, tend to utilize more urea nitrogen for the synthesis of serum protein.

Indications for and limitations of coronary thrombolysis

Experimental studies in dogs with coronary thrombi induced by copper wire confirmed the optimal method of intracoronary thrombolysis, and showed that a high-dose, brief intravenous infusion of urokinase can lead to recanalization. The thrombolytic effects of intracoronary thrombolysin at a rate of 50 IU/kg over 10 minutes are similar to the effects of intracoronary urokinase at a rate 500 IU/kg over 20 minutes. Overall reperfusion rates of 83-86% have been achieved. These results indicate that the thrombolytic effect of thrombolysin is 20 times stronger than that of urokinase. The effect of a brief intravenous infusion of urokinase was less than that of intracoronary urokinase. The reperfusion rate in the same experimental model was 40%. Later, a clinical trial of intracoronary urokinase was performed in 47 patients with acute myocardial infarction who were admitted within 12 hours of the onset of symptoms. In 25 of 33 (75.8%) patients with complete occlusion, selective or ostial infusion of urokinase 500 IU/kg over 20 minutes was successful. When given intravenously, recanalization was achieved in 11 of 15 (73%) patients with complete occlusion who were admitted within 6 hours. Both reperfusion rates were similar except for dosage and the duration of infusion.

[The effects of the intracerebroventricular administration of 5-hydroxytryptamine on hemodynamics in conscious rats. Participation of the serotonin receptor and the sympathetic nervous system]

We have previously reported that the intracerebroventricular (i.c.v.) administration of 5-hydroxytryptamine (5-HT) in conscious rats elicited significant pressor response, which was accompanied with an increase in plasma norepinephrine and the pressor response, was abolished by peripheral phenoxybenzamine pretreatment. For further investigation of the relationship between the serotonergic nervous system and the sympathetic nervous system, the effect of either i.c.v. or intravenous (i.v.) serotonin receptor antagonist, methysergide pretreatment on hemodynamic response to centrally administrated 5-HT was studied. Male Wistar rats weighing approximately 250g were used. On the day before the study, the unilateral carotid artery was cannulated (PE-50) to facilitate mean arterial pressure (MAP) and pressure triggered heart rate (HR) observation. Also, a cannula (PE-10) was inserted stereotaxically into the anterior horn of the lateral cerebral ventricle. The experiment was performed under a conscious and minimumly restrained state. After the observation of resting MAP and HR for at least 20 minutes, 5 microgram of 5-HT was given i.c.v. and MAP and HR were recorded for 50 minutes. Then, the rats were divided into two groups, one group (n = 9) received 1 microgram of i.c.v. methysergide and the other group (n = 10) received 1 mg/kg of i.v. methysergide. Ten minutes after either methysergide i.c.v. or i.v. treatment, 5 microgram of 5-HT was administrated i.c.v. again, and MAP and HR were observed for 30 minutes. Resting MAP and HR were 101.6 +/- 3.0mmHg and 413.8 +/- 20.0/min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects and limitation of CCU--prevention of evolving myocardial infarction

Emergency coronary angiography and intracoronary thrombolysis were performed on 47 patients who were hospitalized within 12 hours from onset of chest pain. It revealed either a severe stenosis (14 pts: stenosed group) or complete occlusion (33 pts) of infarct-related coronary artery. In 25 out of 33 patients (76%) with complete occlusion, reperfusion was achieved after 10 to 20 minutes of intracoronary urokinase (UK) infusion at a rate of 500IU/kg/min (thrombolysed group). The failure to open coronary artery in remaining 8 patients may have been caused by the occlusion of atheroma itself (unsuccessful group). Left ventricular angiography was performed at one month after attack. In unsuccessful group, the mean age was younger and infarct-nonrelated vessel disease was lower frequency compared to other two groups. Ejection fraction in stenosed, thrombolysed and unsuccessful groups were 56.6 +/- 12, 47.5 +/- 14 and 44.3 +/- 5.1%, respectively. Wall motion assessed by point-score system were 6.7, 5.9 and 3.6, respectively (p less than 0.05 in each group). These facts suggest that early recanalization may result in greater reversal of cardiac function. The time to the peak CPK was shortened in stenosed and thrombolysed groups, but, the values of CPK was maximum in thrombolysed group. Rethrombosis was recognized in 2 patients during 1 to 30 months follow-up. No death and no remarkable complications were seen during this intervention, but 4 late deaths were recognized. Thus, early reperfusion by intracoronary UK infusion is effective therapy to improve cardiac function and reduction of death in AMI.

Treatment of borderline hypertension--moderate salt restriction in the treatment of borderline hypertension

Seventeen patients with borderline hypertension and 11 patients with sustained hypertension were instructed to reduce their salt intake to 5-8 g/day. We checked whether or not the patients were following instructions by estimating their 24-hour urinary sodium excretion (UNaV). In borderline hypertension, the UNaV was 5.6 +/- 0.4g/24-hour on a normal salt diet and 3.7 +/- 0.3 (p less than 0.01) on a salt-restricted diet, while in sustained hypertension it was 4.9 +/- 0.3g and 3.6 +/- 0.4g/24-hour (p less than 0.01), respectively. After moderate salt restriction there was a significant fall in blood pressure in the supine, sitting and standing positions in both the borderline and the sustained hypertensives. There was a significant relationship between the fall of mean blood pressure in the supine position and the decrease in the 24-hour urinary sodium excretion, which was corrected for 24-hour creatinine excretion, in overall hypertensive patients (r = 0.39, p less than 0.05). In the borderline hypertensive group, both the systolic and diastolic blood pressure in the sitting position were 8.7 mmHg or 6.3% (p less than 0.01) and 6.2 mmHg or 6.6% lower (p less than 0.01) on salt-restricted diets than those on normal salt diets, respectively. In 9 of 14 patients with borderline hypertension, the diastolic blood pressure moved into the normal range during the salt restriction. We suggest that moderate salt restriction is an effective management of borderline hypertension.

Cardiac involvement in mucolipidosis. Importance of non-invasive studies for detection of cardiac abnormalities

Although mucolipidosis, a fatal metabolic storage disorder, is associated with cardiovascular abnormalities, detailed, non-invasive cardiac examinations have not been well documented. We studied 4 children with type II and type III mucolipidosis, 3 of whom had unequivocal evidence of aortic regurgitation characterized by phonocardiography and M-mode echocardiography. Two-dimensional echocardiography showed an aortic valve prolapse in 3, a mitral valve prolapse in 2 and a tricuspid valve prolapse in 1. The QT interval was prolonged in 2 cases. In 1 autopsy case, we found considerably thickened and retracted aortic, mitral, and tricuspid valves, and accumulation of the foam cells in the myocardium. Echocardiography revealed similar findings in another 3 cases. We conclude that cardiac manifestations in this disorder should be examined carefully particularly by the use of echocardiography which is an excellent technique for detecting cardiovascular abnormalities in mucolipidosis.

Studies on protein nutrition of Papua New Guinea highlanders: nitrogen balance and hematological studies

Studies were made in August 1978 on the N-balance and hematological characteristics of 18 men living in the village of Kalugaluvi (altitude: 1,500m) near Lufa, which is 60km from Goroka, in the Eastern Highland Province of Papua New Guinea. The average daily protein intake on 3 consecutive days was 95.2 +/- 29.3 mgN/kg (35.2 +/- 10.7 g protein/day), and 32.6 +/- 18.7% of the total protein intake was in the form of animal proteins. The calculated nutritional value of the dietary protein, scored according to the 1973 FAO/WHO pattern, was 83.7 +/- 10.6. Urinary and fecal N excretions during the same period were 81.9 +/- 18.7 and 26.3 +/- 11.8 mgN/kg, respectively, giving a nitrogen balance of -13.5 +/- 24.9 mgN/kg. From N-balance data on individuals, the N-intake for maintenance of a zero N-balance was estimated as 116.3 +/- 48.6 mgN/kg (mean 95% confidence interval). Hematological data showed normal or rather high values for hemoglobin (16.90 +/- 1.05 g/100 ml) and serum proteins (8.05 +/- 0.40 g/100 ml). The increased level of serum proteins was associated with an increased globulin level.