Antihypertensive effect of gamma-linolenic acid in spontaneously hypertensive rats

The effects of chronic treatments of adult (aged 16-17 weeks) spontaneously hypertensive rats (SHRs) with different doses of gamma-linolenic acid (GLA) on blood pressure, heart rate, and body weight were studied. Twice-daily injection of SHRs with GLA lowered systolic blood pressure from 175 +/- 4 to 145 +/- 4 mm Hg within 1 week; systolic blood pressure in all three treated groups became stabilized in the normotensive range after 2 weeks of treatment. Control SHRs injected with olive oil showed only a transient decrease in systolic blood pressure on the third day. Heart rate and body weight were not affected by GLA treatment. Withdrawal of GLA treatment resulted in a rapid rise in systolic blood pressure within 1 day from 140 +/- 3 to 165 +/- 3 mm Hg, and it stabilized after 1 week at 191 +/- 5 mm Hg in the three experimental groups. A rapid increase in systolic blood pressure from 175 +/- 5 to 203 +/- 5 mm Hg was also observed in the control group treated with olive oil 1 day after the withdrawal of the treatment. Addition of aspirin (3 mg/kg) with the GLA treatment in olive oil abolished the antihypertensive effect of GLA. In contrast, once-daily treatment with GLA also lowered systolic blood pressure of the SHR, but blood pressure was still in the hypertensive range (170 +/- 6 mm Hg). Systolic blood pressure of control SHRs treated with olive oil was not affected. Plasma from untreated SHRs contained a small amount of GLA. One hour after the injection, the plasma level of GLA increased. We conclude that GLA when given twice daily is an effective antihypertensive agent in the SHR.

Evidence that extracellular signal-regulated kinases are the insulin-activated Raf-1 kinase kinases

The Raf-1 proto-oncogene protein kinase can be phosphorylated and activated after stimulation of cells with insulin and a variety of other growth factors and mitogens. We recently presented evidence that insulin and certain other growth factors activated one or more Raf-1 kinase kinase activities (Lee, R.M., Rapp, U. R., and Blackshear, P.J. (1991) J. Biol. Chem. 266, 10351-10357). In the present study, four peaks of Raf-1 kinase kinase activity were identified after anion-exchange chromatography of cell lysates, and two of these were activated by insulin. Further chromatographic characterization of these two peaks of insulin-activated kinase activity indicated that they contained three apparently distinct kinase activities. Two of these activities comigrated with immunoreactive extracellular signal-regulated kinases (ERK) 1 and 2 (mitogen-activated protein kinase) through three different chromatographic separations. Both ERK1 and ERK2 phosphorylated Raf-1 with reasonably high affinity (Km for ERK1 = 90 nM; Km for ERK2 = 120 nM), and produced similar, complex phosphopeptide maps; both kinases also phosphorylated myelin basic protein. The third kinase activity also phosphorylated Raf-1 and myelin basic protein but did not comigrate exactly with either immunoreactive ERK1 or ERK2. We conclude that two and possibly three insulin-activated Raf-1 kinase kinases are members of the ERK family.

Combined effect of neonatal sympathectomy and adrenal demedullation on blood pressure and vascular changes in spontaneously hypertensive rats

Neonatal sympathectomy using a combined treatment with antiserum to nerve growth factor and guanethidine during the first 4 weeks after birth was carried out in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Bilateral adrenal demedullation was performed in 4-week-old sympathectomized SHR and WKY rats. The development of hypertension in SHR was prevented by sympathectomy, but the blood pressure (BP) was still higher than in age-matched WKY rats. Demedullation reduced the BP of sympathectomized SHR to the same level as that of WKY rats. Heart rates of SHR and WKY rats were not affected by the treatments. Morphometric measurements of the mesenteric arteries showed that sympathectomy significantly reduced the medial mass in the mesenteric arteries of SHR, mainly through a reduction in the number of smooth muscle cell layers. In sympathectomized SHR, demedullation increased the lumen size of muscular arteries under maximally relaxed conditions, which might explain the further reduction in BP in these animals. Demedullation in sympathectomized SHR and WKY rats caused a decrease in smooth muscle cell layers in the superior mesenteric artery, but the same treatment resulted in a slight increase in the number of smooth muscle cell layers in the large and small mesenteric arteries of SHR and WKY rats. Adventitial area was increased in some mesenteric arteries of SHR and WKY rats by sympathectomy, and demedullation caused a further increase in the size of adventitia in WKY rats. Heart weight in SHR was normalized to the level found in WKY rats by sympathectomy and demedullation. We conclude that in sympathectomized SHR, the elevated BP was maintained by the adrenal medulla.

Evidence for one or more Raf-1 kinase kinase(s) activated by insulin and polypeptide growth factors

The protein product of the Raf-1 proto-oncogene is a protein serine/threonine kinase that is activated after stimulation of cells with insulin and other mitogens. To investigate the mechanism of this activation, we used purified Raf-1 expressed in E. coli as a substrate for a putative Raf-1 protein kinase kinase. In three different insulin-sensitive cell types, insulin activated Raf-1 kinase kinase activity in crude cytosolic cellular fractions. The insulin stimulation of this activity was evident as early as 2 min after exposure to insulin, maximal at 5-8 min, and inapparent at 15 min. Phosphoamino acid analysis of phosphorylated Raf-1 revealed that serine was the primary phosphate acceptor for the insulin-activated kinase or kinases; small amounts of phosphothreonine were also detected. The insulin effect occurred in cells depleted of protein kinase C, and in extracts depleted of endogenous Raf-1 kinase by immunodepletion; these data argue against protein kinase C or Raf-1 kinase itself being the insulin-stimulated activity. The insulin-activated kinase or kinases phosphorylated the Raf-1 protein on multiple sites in vitro, as evidenced by tryptic mapping; at least some of these appeared to overlap with sites phosphorylated in response to serum in intact cells. Several other mitogens and growth factors stimulated Raf-1 kinase kinase activity, including epidermal growth factor, platelet-derived growth factor, fibroblast growth factor, serum, and phorbol 12-myristate 13-acetate. This insulin- and mitogen-stimulated Raf-1 kinase kinase activity may play a role in mediating the phosphorylation and possibly the activation of the Raf-1 kinase by insulin and other growth factors.

Arterial vasodilation and cardiovascular structural changes in normotensive rats

In normotensive rats, the arterial vasodilator minoxidil causes right ventricular hypertrophy (RVH) and eccentric left ventricular hypertrophy (LVH). To assess whether this trophic effect of minoxidil extends to the vasculature and to examine possible mechanisms involved, alterations in cardiac and arterial (superior, large and small mesenteric arteries, carotid and basilar arteries) structure were evaluated in relation to changes in indexes of cardiac volume load and cardiac and arterial sympathetic activity during long-term (35 and 70 days) treatment of normotensive rats with minoxidil alone or in combination with the diuretic hydrochlorothiazide (HCTZ). Minoxidil alone increased LV and RV weights, LV internal diameter, and medial area of the superior mesenteric artery but did not affect any of the other arteries evaluated. When combined with HCTZ, long-term minoxidil caused concentric LVH rather than eccentric LVH and no longer increased the medial area of the superior mesenteric artery. Neither treatment had any persistent effect on blood pressure, heart rate, or plasma catecholamines. However, minoxidil significantly increased cardiac and arterial (superior and large mesenteric artery) norepinephrine turnover rates, cardiac filling pressures, and plasma and blood volumes. When combined with HCTZ, short-term (1 wk) minoxidil still increased cardiac filling pressures. However, intravascular volume expansion during chronic treatment was significantly attenuated. These results suggest that chronic cardiac volume load appears to determine the type of cardiac hypertrophy induced by a nonhemodynamic mechanism (possibly cardiac sympathetic activity) activated by minoxidil. Intravascular volume expansion or increased arterial flow appears to be responsible for medial hypertrophy of the superior mesenteric artery, but absence of a trophic response in other arteries suggests that another, local mechanism contributes.

Effect of hydralazine on the mesenteric vasculature of hypertensive rats

To test whether structural alterations observed in the mesenteric vasculature of Wistar-Kyoto spontaneously hypertensive rats (SHR) were dependent on the presence of hypertension, male SHR and Wistar-Kyoto normotensive (WKY) rats were treated in utero and postnatally with hydralazine up to 28 weeks of age. Treated SHR, WKY, and untreated WKY rats had comparable blood pressures that were less than those of untreated SHR. Treatment altered the dimensions of the superior mesenteric, intermediate-sized, and small arteries of the mesenteric vasculature. In the case of the superior mesenteric artery and intermediate vessels, hydralazine treatment increased the lumen and medial cross-sectional areas of the arteries in WKY rats and slightly decreased both parameters in SHR. Within the small arteries, treatment significantly increased the lumen size in SHR but not WKY rats and had no significant effect on the media of the vessels. Despite the above alterations, the media-to-lumen cross-sectional area ratios remained significantly elevated in SHR over WKY rats in both the treated and control groups of animals within all classes of arteries. The results indicate that there is an inherent increase in the quantity of media surrounding the arteries of SHR when compared with WKY rats that cannot be abolished by normalizing the blood pressure in utero and postnatally with hydralazine treatment. In SHR, such changes persist not only in arteries that exhibit an increase in the media-to-lumen ratio before hypertension but also in the superior mesenteric artery in which an increase in the ratio occurs after hypertension development.

Prevention of hypertension and vascular changes by captopril treatment

Treatment of female spontaneously hypertensive rats (SHR) and control Wistar-Kyoto (WKY) rats with captopril was carried out by the addition of the drug in the drinking water throughout pregnancy and lactation and after weaning. At 28 weeks of age, average systolic blood pressure of treated SHR was 113 +/- 3 mm Hg, which was below that of control SHR (188 +/- 3 mm Hg) and WKY rats (124 +/- 3 mm Hg). Body weight and heart rate of the SHR were not affected by the treatment. Tissue level of catecholamines was increased by captopril treatment in the superior cervical ganglia but remained unchanged in the plasma, heart, mesenteric arteries, and the adrenal glands of both SHR and WKY rats. Left ventricular weight, wall thickness, and internal diameter of the left ventricle in the SHR were reduced by the treatment. Morphometric measurements of the mesenteric arteries showed that vascular alterations present in the control SHR were prevented by the treatment. In the superior mesenteric artery and large mesenteric artery, smaller lumen size at maximal relaxation found in the control SHR was normalized to the level of the WKY rats. Hypertrophy of the medial wall in the superior mesenteric, large and small mesenteric arteries, and an increase in the number of smooth muscle cell layers in the large mesenteric artery of the SHR were prevented by the treatment. Perfusion study of the mesenteric vascular bed showed that reactivity of these vessels to norepinephrine was reduced, and sensitivity to norepinephrine (as determined by the effective dose that causes 50% of maximal response) was increased in the SHR by captopril treatment. Sensitivity of the tail artery in response to norepinephrine was not altered by the treatment. We conclude that long-term treatment with captopril of SHR before and after birth prevented the development of hypertension, structural and functional alterations of the mesenteric arteries, and cardiac hypertrophy.

Interaction between sympathetic nervous system and adrenal medulla in the control of cardiovascular changes in hypertension

The role of the sympathetic nervous system and adrenal medulla in the development of cardiovascular changes and hypertension was studied in spontaneously hypertensive rats (SHRs), and the results compared with age-matched normotensive Wistar-Kyoto (WKY) rats. Sympathectomy was initiated in newborn rats through daily injection with antiserum to nerve growth factor for 1 week, followed by daily injection with guanethidine for 3 weeks. Removal of the adrenal medulla was carried out in 4-week-old rats after the last guanethidine injection. Such a combination treatment was effective in permanently preventing the development of hypertension in the SHRs, and the blood pressure was maintained at the level of WKY rats. The heart rate of the SHRs and WKY rats was not affected by such treatment. Hypertrophy of the heart and of the vessel wall in the mesenteric arteries was also prevented by such treatment. We conclude that in the SHR, the sympathetic nervous system and the adrenal medulla are essential for the development of cardiovascular changes and hypertension.

Opposite effects of arterial vasodilators on cardiac vs. arterial hypertrophy and sympathetic activity in spontaneously hypertensive rats

To investigate whether cardiac and arterial structure and sympathetic activity changes in a similar fashion during chronic arterial vasodilation, we evaluated the morphology and sympathetic activity of the mesenteric arterial bed and the left (LV) and right (RV) ventricles of 16-week-old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHRs) after 35 and 70 days of treatment with the arterial vasodilator minoxidil. The minoxidil-induced antihypertensive response was associated with an increase in ventricular sympathetic activity, potentiation of RV hypertrophy (RVH), and the development of eccentric LV hypertrophy (LVH). In the mesenteric arterial bed, minoxidil decreased the sympathetic activity, increased the lumen of the superior mesenteric artery, and decreased the medial area of the large and small mesenteric arteries. We conclude that the contrasting effects of minoxidil on cardiac vs. arterial structure may--in part--relate to selective effects on regional sympathetic activity.

Changes of beta-adrenoceptors in the aortic muscle cells of spontaneously hypertensive rats

The characteristics of [125I]monoiodocyanopindolol (ICYP) binding to beta-adrenoceptors of cultured aortic smooth muscle cells derived from 4-week-old spontaneously hypertensive rats (SHR) and the Wistar-Kyoto normotensive rats (WKY) were examined. During optimization of the binding assays, we found that the specific binding of ICYP by intact cells was masked by a high level of nonspecific ICYP accumulation in intact cells presumably owing to the lipophilic nature of ICYP. Optimal specific ICYP binding requires that the cells be gently lysed with hypotonic dilution followed by a freeze-and-thaw cycle. Under most experimental conditions tested, the total number of ICYP binding sites in WKY aortic muscle cells was considerably and consistently smaller than that in SHR cells. There was no difference in the Kd values for ICYP binding to SHR and WKY cells. However, when ICYP binding was carried out using crude membrane fractions with well-defined plasma membrane content isolated from aortic muscle strips of adult rats, we found no difference in the number of beta-adrenoceptor sites between SHR and WKY. Morphological evidence indicated that cultured SHR aortic muscle cells contained a greater proportion of larger cells with multinuclear features. These results suggest that an increase in the number of beta-adrenoceptor density per cell in SHR may be associated with cellular hypertrophy of aortic smooth muscle cells. We conclude that under cultured conditions, a higher incidence of polyploid smooth muscle cells in the SHR as compared with WKY was expressed earlier than under in vivo conditions. Therefore, the interpretation of results obtained from cultured cell studies in relation to under in vivo conditions should be exercised with caution.

Increased sympathetic innervation in the cerebral and mesenteric arteries of hypertensive rats

The density of catecholamine-containing nerve fibers was studied in the cerebral and mesenteric arteries from normotensive Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke-prone SHR (SHRSP) in the growing (SHR, WKY) and adult (SHR, SHRSP, WKY) animals. Cerebral arteries from SHR showed an increased adrenergic innervation from day 1. The nerve plexuses reached an adult pattern earlier in SHR than in WKY. The arteries from adult SHR and SHRSP (22 weeks old) showed a markedly higher nerve density than WKY. There was a positive linear correlation between blood pressure and nerve density for four cerebral arteries. The mesenteric arteries were not innervated at birth. However, hyperinnervation of these arteries in the SHR was already present at 10 days of age as compared with WKY. Sympathectomy with anti-nerve growth factor and guanethidine caused a complete disappearance of fluorescent fibers in the mesenteric arteries from SHR and WKY, and in the cerebral arteries of WKY. The same procedure caused only partial denervation of the cerebral arteries from hypertensive animals. We postulate that the increase in nerve density in the cerebral arteries from the hypertensive rats may contribute to the development of arterial hypertrophy in chronic hypertension through the trophic effect of the sympathetic innervation on vascular structure.

The management of patients with suspected early postoperative small bowel obstruction

A 10-year review of 101 patients sustaining an early postoperative small bowel obstruction within 30 days of celiotomy was carried out. Signs, symptoms, lab tests, and x-rays did not indicate which patients required operation. Twenty-three patients were operated on for either failure to resolve their obstruction or because it was feared that ischemic bowel was present. In none of these patients, nor the 78 patients who resolved without reoperation, did dead bowel occur. Early postoperative small bowel obstruction was most often due to adhesions and inflammatory processes. Seven patients died (6.9%), three in the operated and four in the nonoperated group. Because ischemic bowel is very unlikely in patients with early postoperative small bowel obstruction, we advise 10 to 14 days of nasogastric suction initially; after this, improvement is unlikely without reoperation.

Autoradiographic study of smooth muscle cell proliferation in spontaneously hypertensive rats

1. The rate of smooth muscle cell proliferation in age-matched 1-4-week-old spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats was compared using autoradiography. 2. Labelling index, defined as labelled cells/sum of labelled and unlabelled cells x 1000, was obtained from perfusion-fixed superior mesenteric and large mesenteric arteries. 3. In the large mesenteric arteries, the smooth muscle cell labelling indices were similar between the SHR and WKY at all age groups, except at 1 week of age when the smooth muscle labelling index was higher in the SHR. 4. In the superior mesenteric arteries, labelling indices were similar between the rat strains at all age groups. 5. We conclude that, in the SHR, a rapid proliferation of smooth muscle cells in the large mesenteric arteries occurred during the first week of life. This resulted in a higher number of smooth muscle cell layers in the media of muscular arteries. 6. The increased proliferation may play a role in the subsequent development of hypertension in the SHR.

Alterations in c-abl gene methylation in cells transformed by phagocyte-generated oxidants

DNA from 10T1/2 cells transformed by activated neutrophils was analyzed for restriction length polymorphisms (RFLPs) in cellular homologues of retroviral oncogenes, and consistent RFLPs were found in MspI sites of the c-abl gene of all PMN-transformed cell lines. MspI digests probed with c-myc, v-Ki-ras, v-Ha-ras or v-mos showed no RFLPs, and none were observed in EcoRI, PstI, HindIII, BamHI, SmaI, Sau3a, MboI, HhaI, or TaqI digests probed with v-abl. Analysis of HpaII digests supports the conclusion that c-abl RFLPs result from differential methylation of the CCGG HpaII/MspI recognition sequence. MspI RFLPs in the c-abl gene may provide markers for oxidant-related genetic injury.

Ventilatory support in the management of septic patients

The use of mechanical ventilation in septic patients with or without ARDS remains under the category of supportive care. It is the task of clinicians to properly manage the ventilated patient and to prevent complications and treat them as soon as possible, if they arise. All clinicians eagerly await the introduction of agents that will either attenuate the inflammatory response in patients with the septic syndrome prior to the development of ARDS or assist in the healing of the acute injury.

Vascular changes associated with deoxycorticosterone-NaCl-induced hypertension

Rats were injected with deoxycorticosterone (DOC) and salt was added to the drinking water (DOC/NaCl) for 3 weeks. Approximately half of the animals became hypertensive (DOC-H), whereas the remainder showed no increase in blood pressure (DOC-N) compared to age-matched, untreated controls. Morphometric analysis of the alterations in the arteries of the mesenteric bed was carried out in vessels fixed at maximum relaxation. Alterations were observed in the arteries, some of which were related to hypertension, but not to treatment, and some were due to treatment alone. The alterations within the arteries of the mesenteric bed depended in part on the type of artery, i.e. elastic, muscular or arteriolar. An increase in lumen area, in intimal area, and in the area of the media was seen in all types of arteries from DOC-H, but not in either group of normotensive animals. The medial hypertrophy was positively correlated with the increase in blood pressure; and was due to an increase in the number of smooth muscle cell layers in the elastic and muscular arteries, and probably to smooth muscle cell hypertrophy in the arterioles. The adventitial area was increased only in the elastic and muscular arteries. Endothelial injury, degeneration of the basement membrane, loss of heparan sulfate proteoglycan and intimal edema was observed in all the DOC/NaCl-treated animals, but was more severe in those which were also hypertensive. Hypertrophy of the heart and kidneys were observed in both normotensive and hypertensive DOC/NaCl-treated animals. These data indicate that changes in the rat cardiovascular system can be induced by DOC/NaCl treatment in the absence of hypertension, but also that hypertension is associated with specific arterial structural alterations, which vary according to the type of artery.

Alterations of elastin and elastase-like activities in aortae of diabetic rats

The elastin content of the aortic muscle and the elastase-like activity of the extracts of aortic muscle were studied in spontaneously diabetic BB rats and in rats made diabetic by a single bolus i.v. injection of alloxan. In both modes of diabetes, the total alkaline-insoluble aortic elastin content was significantly reduced in diabetic rats compared to that in the corresponding control rats. This reduction in aortic elastin was also accompanied by a consistent increase in the elastase-like activities of the aortic extracts prepared from the same tissues. Such a reciprocal relationship between aortic elastin content and elastase-like activity has previously been reported in rats with malignant hypertension. Since the rats used in this study were not hypertensive, the altered elastin metabolism observed in this work is likely to be a manifestation of diabetic disease and may in part account for the vascular changes associated with diabetes mellitus.

Prenatal and postnatal hydralazine treatment does not prevent renal vessel wall thickening in SHR despite the absence of hypertension

Previous studies in our laboratory have shown that the renal blood vessels of 21-week-old Wistar-Kyoto spontaneously hypertensive rats exhibited thicker vascular walls than age matched Wistar-Kyoto normotensive rats. Morphometric analysis of the relaxed renovasculature revealed an increase in the cross-sectional area of the media, which in most cases was associated with an increase in the number of smooth muscle cell layers. To test if these structural changes occur in the absence of raised blood pressure, hydralazine was administered to spontaneously hypertensive rats and normotensive controls prior to and during pregnancy (100 ml/l drinking water), and to the newborn males up to 21 weeks of age (16.9 mg/kg/day by gavage until weaning followed by 100 mg/l in the drinking water). Treated animals were compared with untreated rats. Treatment prevented hypertension development in spontaneously hypertensive rats but did not alter the structural changes found in untreated animals with hypertension. At 21 weeks of age, hydralazine-treated spontaneously hypertensive rats had similar wall-to-lumen area ratios, medial cross-sectional areas and numbers of medial smooth muscle layers as untreated hypertensive rats while these parameters were greater in treated and untreated spontaneously hypertensive rats than in either treated or untreated normotensive controls. Withdrawal of hydralazine from 26-week-old spontaneously hypertensive rats that had been treated in utero and postnatally and had normal blood pressures throughout life resulted in the rapid onset of hypertension. Our results show that renal vascular wall thickening in spontaneously hypertensive rats occurs in the absence of high blood pressure and therefore is not a secondary effect of raised blood pressure.

Structural and reactivity alterations of the renal vasculature of spontaneously hypertensive rats prior to and during established hypertension

The renal vasculature of Wistar Kyoto spontaneously hypertensive rats (SHR), prior to (4-5 week) and during established hypertension (21 week) and those of age-matched Wistar Kyoto normotensive rats (WKY) were morphometrically and pharmacologically studied. Under dilated conditions, the vascular resistances (RVR) of the isolated kidneys of young and adult SHR were similar to WKY. Morphometric measurements of renal vasculature indicated that the cross-sectional area of the intima and adventitia and its subcomponents were similar in adult SHR and WKY. With the exception of the preglomerular arterioles, all the renal arteries of adult SHR exhibited elevated cross-sectional quantities of total media, medial smooth muscle cells (SMCs), and extracellular space. Analysis of the SMCs indicated the presence of increased numbers of SMC layers and/or an increase in the SMC volume-to-surface area ratio in arteries sampled from adult SHR. Vascular contraction produced by infusing norepinephrine, BaCl2, angiotensin II, or by stimulating the renal nerves elevated the RVR to a greater degree in adult SHR than in WKY. The sensitivity of the renal vasculature to the various contractile agents was similar in adult SHR and WKY. When compared with WKY, prehypertensive SHR also exhibited increased cross-sectional quantities of arterial media and elevated amplitudes of RVR change in response to norepinephrine and renal nerve stimulation. However, the vascular contractile sensitivity to norepinephrine was reduced. Our results indicate that renovascular wall thickening and the hypercontractile reactivity associated with such a change precedes hypertension in SHR. In prehypertensive SHR, elevations in RVR might be counterbalanced by a decreased norepinephrine sensitivity. An increase in the norepinephrine contractile sensitivity and further vascular thickening with age could elevate the RVR and establish hypertension.

Airway epithelial damage in premature infants with respiratory failure

To evaluate the evolution of airway epithelial damage in premature infants developing bronchopulmonary dysplasia (BPD), a detailed quantitative light and electron microscopic evaluation was performed of the major airways in 3 infants who succumbed from respiratory failure. The 3 infants ranged from 24 to 28 wk gestational age and died after 14 h, 10 days, and 6 months of life. The tracheal epithelium was severely damaged with up to half of the epithelium being denuded in each infant. The infants who died after 14 h and after 10 days demonstrated minimal epithelial denudation in more distal bronchial divisions. However, gross and microscopic abnormalities of the ciliated component of the epithelium were common. In the infant with severe established BPD, there was extensive epithelial denudation and ciliary abnormalities out to the fourth bronchial division. The percentage of goblet cells in the total cell population decreased from proximal to distal major airways, with the lowest percentage being seen in the infant with established BPD. These studies demonstrate the respiratory failure and assisted ventilation in the human neonate is associated with severe epithelial damage in the trachea and proximal bronchi. It suggests that the difficulty in clearing airway secretion results from a defect in mucociliary transport system rather than from an increase in airway secretion.

Peptide-containing nerves around blood vessels of stroke-prone spontaneously hypertensive rats

The distribution and density of nerves containing vasoactive intestinal polypeptide, substance P, and neuropeptide Y around the cerebral and peripheral blood vessels of stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) were studied using an indirect immunofluorescence technique. Neonatal sympathectomy of SHRSP with anti-nerve growth factor and guanethidine was also carried out to study the effect of sympathectomy on the distribution of these nerves. Vasoactive intestinal polypeptide nerve density was higher in the veins and superior mesenteric artery of SHRSP than of WKY and lower in the cerebral arteries of SHRSP than of WKY, but no difference was found in the muscular mesenteric arteries. Sympathectomy reduced the density of these nerves in all the peripheral vessels but had little effect on the cerebral arteries. Density of substance P nerves was similar between SHRSP and WKY in the peripheral vessels but higher in the cerebral arteries of WKY than of SHRSP. Sympathectomy reduced the density of these nerves in the peripheral vessels but increased the density in some cerebral arteries of SHRSP. Neuropeptide Y nerve density was higher in the peripheral blood vessels of SHRSP than of WKY, and no difference was found in the cerebral arteries. Sympathectomy almost completely removed these nerves in the peripheral vessels but had no effect on the cerebral arteries. We suggest that some of the differences in nerve density between SHRSP and WKY, especially those in the peripheral blood vessels, may be related to the development of hypertension in the SHRSP.

Ultrastructure and morphometric measurements of mesenteric arteries from newborn spontaneously hypertensive rats

A morphometric and ultrastructural study of superior mesenteric arteries and large mesenteric arteries from newborn spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) was carried out. Morphometric measurements showed that in both vessel types, cross-sectional areas of the lumen and vessel wall components (e.g., media, adventitia) were similar between SHR and WKY. There was also no ultrastructural difference between SHR and WKY in the two types of arteries. We therefore conclude that vascular alterations found in older SHR take place after birth.