Kinins are implicated of the hypotensive effect of acidic fibroblast growth factor

Acidic fibroblast growth factor causes an acute and transient nitric oxide-dependent hypotensive effect in experimental animals. However, this response is not found, or is very small, in vitro. We hypothesized that plasma mediators, such as kinins, are involved in aFGF-induced hypotension. We studied the hypotensive effect of intravenous aFGF (1 microg) in control Wistar rats, and compared this response to that in Wistar rats treated with a bradykinin receptor antagonist Na-adamantaneacetyl-D-Arg-(Hyp3,Thi5,8,D-Phe7]-brad yki nin), in kininogen-deficient Brown-Norway-Katholiek (BNK) rats, and in rats depleted of kininogen after repeated treatment with ellagic acid. FGF was administered in the jugular vein and mean arterial pressure was measured through a femoral artery catheter. Following treatment with the bradykinin receptor antagonist, the hypotensive effect of aFGF was reduced 38% with 58 microg of antagonist and by 60% with the 420 microg dose (9 +/- 1 vs 22 +/- 3mm Hg, p<0.01). Mean blood pressure decrease was 12 +/- 1 in BNK rats (p<0.01, vs control) and 10 +/- 2 mm Hg in kininogen-depleted ellagic acid-treated rats (p<0.05, vs control). These findings implicate kinins as necessary mediators for the hypotensive effect of aFGF in vivo. A full hypotensive effect of aFGF requires sufficient amounts of kininogens, the precursor molecules of kinins, as well as bradykinin receptors.

Serum levels of basic fibroblast growth factor in acute myocardial infarction

As it has been reported that basic fibroblast growth factor (bFGF) is a circulating peptide and bFGF gene expression is increased after myocardial ischemia, this study was designed to investigate the serum levels of bFGF in patients with acute myocardial infarction (AMI). Using a bFGF enzyme-linked immunoassay, bFGF levels were determined in venous blood of 15 patients with AMI on admission, at 10 days, and 30 days after infarction, and of 15 age-matched healthy volunteers who were used as controls. bFGF serum levels on admission were similar to normal values (7.48 +/- 2.3 vs 8.14 +/- 2.9 pg/ml). However, they significantly increased (16.82 +/- 3.4 pg/ml; p <0.05) 10 days after the onset of AMI, and at 30 days they returned to baseline (7.07 +/- 2.9 pg/ml). The increased bFGF levels at the second week post AMI suggest that bFGF plays an important role in mediating the development of coronary collateral circulation after myocardial ischemia in humans.

Role of fibroblast growth factors in neural trauma

Following a traumatic insult to the adult mammalian central nervous system (CNS), a complex of molecular and cellular responses ensues. Several peptide growth factors seem implicated in the CNS traumatic response. Furthermore, several of them, like some of the members of the fibroblast growth factor family of polypeptides seem to have a protective role. The purpose of this article is to point toward some basic aspects of FGFs neuroprotective activity against traumatic CNS injuries for the development of novel therapeutic strategies in neural trauma.

A non-mitogenic form of acidic fibroblast growth factor reduces neutrophil infiltration in rat ischemic reperfused heart

We studied the effects of a non-mitogenic form of acidic fibroblast growth factor (aFGF) on neutrophil infiltration in a rat model of myocardial ischemia (20 min) and reperfusion (24 hr). Neutrophil infiltration, as assessed by measurement of myeloperoxidase (MPO) activity was compared in homogenates of the infarcted left ventricle and the non-infarcted septum which was used as a reference of normal tissue. Myocardial ischemia followed by reperfusion resulted in severe myocardial injury and high cardiac MPO activity indicative of neutrophil accumulation in the ischemic myocardium. A systemic bolus (i.v.) of aFGF (2.6 microg) administered immediately after myocardial ischemia, significantly reduced (p<0.001) the MPO activity in the ischemic reperfused left ventricle compared to vehicle-treated rats. Furthermore, aFGF significantly attenuated tissue damage and neutrophil accumulation in the area at risk after myocardial ischemia and reperfusion as assessed by conventional histology. The mechanism of this protective effect appears to be related to inhibition of neutrophil extravasation, a critical step in neutrophil-induced myocardial reperfusion injury. Thus, non-mitogenic aFGF appears as an effective cardioprotective treatment for myocardial infarction.

Osteopromotion for cranioplasty: an experimental study in rats using acidic fibroblast growth factor

BACKGROUND

Many growth factors influence the bone healing cascade. Furthermore, the occasional failure of bone repair may in part be due to perturbation in the activation of local growth factors. Local activation of fibroblast growth factors (FGFs) at the fracture site may serve to increase neovascularization, and induce early granulation formation that can affect bone healing.

METHODS

We have performed a rat parietal (6 x 3 mm) critical size defect (CSD). Human recombinant acidic fibroblast growth factor (hraFGF) imbided in agarose was topically administered at the craniectomy site. Control animals received agarose alone in the same manner. Three weeks after surgery, osteopromotion was histologically evaluated.

RESULTS

hraFGF-treated animals show a continuous bridge of regenerated bone extending from one edge of the defect to the other. None of the parietal defects that had been treated with agarose contained new bone in the central portion.

CONCLUSION

Our results suggest an important role of FGFs to promote large cranioplasty repair and support the use of these proteins as an alternative choice for bone grafts and bone substitutes.

Protective effects of acidic fibroblast growth factor against cardiac arrhythmias induced by ischemia and reperfusion in rats

An in vivo study has been conducted to evaluate the effect of acidic fibroblast growth factor (aFGF) on cardiac arrhythmias which occur in transient myocardial ischemia followed by reperfusion. In a rat model of myocardial ischemia and reperfusion, cardiac arrhythmias were assessed during the first three minutes of reperfusion. Systemic administration of 2.6 micrograms aFGF just before coronary recirculation resulted in a significant reduction in incidence and severity of ventricular extra beats (VEBs), ventricular tachycardia (VT) and ventricular fibrillation (VF), compared with control rats (VT incidence: 30% vs 80%, VF incidence: 10% vs 40%; episodes of VT: 4.1 +/- 0.34 vs 8.8 +/- 0.95; episodes of VF: 4.8 +/- 0.32 vs 11.5 +/- 1.47). Our results suggest a novel role for FGFs as potential antiarrhythmic agents.

Protection of rat myocardium by mitogenic and non-mitogenic fibroblast growth factor during post-ischemic reperfusion

The effects of acidic fibroblast growth factor (FGF-1) and basic fibroblast growth factor (FGF-2) and a non mitogenic form of FGF1 on myocardial ischemia and reperfusion were assessed. Rats underwent 10 minutes of coronary artery occlusion followed by 24 hours of reperfusion. Creatinine kinase content of the affected myocardium showed that both fibroblast growth factors 1 and 2 effectively protected against ischemia reperfusion injury (p < 0.01), and that the vasoactive but nonmitogenic form of the FGF1 was equally protective (p < 0.01 versus control + vehicle). The results were confirmed by light and electron-microscopy histological studies. Histological evaluations after treatment with the non-mitogenic fibroblast growth factor 1 showed that it did not generate the severe hyperplasia and connective tissue disorganization observed with the native mitogenic proteins. The possibility of using a non-mitogenic form of fibroblast growth factor for cardio-protection circumvents many of the potentially undesirable effects that may derive from systemically introducing broad spectrum acting fibroblast growth factors in vivo. This myocardial protection observed 24 hours after the treatment with fibroblast growth factors, and the efficacy of the non-mitogenic form of the protein, also suggest that the protective effect of fibroblast growth factors may be due to the increased blood flow rather than to angiogenesis.

Loss of basic fibroblast growth factor in the subcommissural organ of old spontaneously hypertensive rats

The immunocytochemical localization of basic fibroblast growth factor (bFGF) was studied in subcommissural organ (SCO) of aged-matched normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats at 10, 14 and 18 months of age using a polyclonal antibody against bFGF. The bFGF-like immunoreactivity (bFGF-ir) was observed in SCO ependymal cells of young and old normotensive rats. However, a progressive loss of bFGF-immunopositive ependymal SCO cells was observed with age in SH rats (27.24, 57.5 and 96.9% in 10, 14 and 18 months old respectively) compared with aged-matched WKY normotensive rats. Considering the potential role of the SCO in sleep regulation and sodium homeostasis, which are altered in essential hypertension, these data show a new neuroendocrine anomaly to be added to the many others previously observed in this rat strain, when they develop hypertension as they get old.

Sleep promoting effects of intravenously administered acidic fibroblast growth factor

The influence of acidic fibroblast growth factor (aFGF) on sleep was studied in conscious rabbits. An intravenous (i.v.) bolus injection of aFGF induced a significant increase in sleep duration in comparison with animals that received vehicle solution. Somnogenic effects were obtained 30 min following i.v. aFGF administration and lasted about 75 min. Furthermore, the somnogenic effects of aFGF were prevented by pretreatment with the nitric oxide synthase inhibitor L-NAME. Our findings demonstrate a somnogenic effect of aFGF which requires crossing the blood-brain barrier (BBB) and implicate that nitric oxide sleep pathway may be involved in this biological effect.

Fibroblast growth factor decreases locomotor activity in rats

The spontaneous locomotor behavior of rats receiving subcutaneous administration of either acidic or basic fibroblast growth factors was recorded in an activity cage. We report that doses between 1 and 100 micrograms/kg significantly decreased the horizontal and vertical activity, as well as the exploratory and stereotypy behavior of the rats. These effects of fibroblast growth factors seem to be specific since (i) they were cancelled by protein hydrolysis and anti-fibroblast growth factor antibodies, (ii) they were unrelated to their hypotensive activity and (iii) they were not attributable to their high structural similarity with the cytokine interleukin-1. Thus fibroblast growth factors did not show any thermogenic activity, did not affect the hypothalamic output of corticotropin-releasing factor and did not change the plasma levels of corticosterone. Pretreatment of the rats with a specific inhibitor of brain nitric oxide synthase prevented the effects of fibroblast growth factors, suggesting the involvement of nitric oxide in these behavioral modifications. Our results contribute to the accumulating evidence describing non-mitogenic activities of fibroblast growth factors.

Correction of hypertension by normalization of endothelial levels of fibroblast growth factor and nitric oxide synthase in spontaneously hypertensive rats

Acidic and basic fibroblast growth factors (FGFs) share a wide range of diverse biological activities. To date, low levels of FGF have not been correlated with a pathophysiologic state. We report that blood vessels of spontaneously hypertensive rats are shown to be associated with a marked decrement in endothelial basic FGF content. This decrement correlates both with hypertension and with a decrease in the endothelial content of nitric oxide synthase. Restoration of FGF to physiological levels in the vascular wall, either by systemic administration or by in vivo gene transfer, significantly augmented the number of endothelial cells with positive immunostaining for nitric oxide synthase, corrected hypertension, and ameliorated endothelial-dependent responses to vasoconstrictors. These results suggest an important role for FGFs in blood pressure homeostasis and open new avenues for the understanding of the etiology and treatment of hypertension.

Is glia disfunction the initial cause of neuronal death in ischemic penumbra?

The supportive role of glial cells on neuronal function and survival has been studied in anesthetized rats by using the selective gliotoxin fluorocitrate. Disabling glia operation reproduced many features of ischemic penumbra. An initial mild acidosis and increased interstitial potassium but not glutamate was followed after 3-4 h by repetitive spreading depression waves. These gradually provoked higher levels of acidosis, potassium and glutamate, gradual neuronal function decay and finally, neuron death. We conclude that neurons become highly vulnerable to spreading depression waves only in absence of normal glia operation. Our findings directly associate early glial disfunction to neuronal loss and lead to new insights for the understanding of ischemic pathology.

Prostanoid production in rabbit corpus cavernosum. II. Inhibition by oxidative stress

PURPOSE

To investigate the effects of reoxygenation following hypoxia on prostanoid production in rabbit penile corpus cavernosum tissue (RCC) in organ culture.

MATERIALS AND METHODS

Strips of RCC were incubated in organ culture media under either 21% O2 (control, PO2 approximately 167 mm.Hg) or 0% O2 (hypoxia, PO2 approximately 27 mm.Hg) followed by a reoxygenation period with 21% O2, in the presence or absence of exogenous arachidonate, Tiron or catalase. Prostanoids were measured in collected media by radioimmunoassay. Malondialdehyde levels were measured in RCC following exposure to either control or hypoxia-reoxygenation conditions.

RESULTS

Under hypoxic conditions, basal release of prostanoids (PGI2, PGF2 alpha, PGE2 and TXB2) was inhibited. Although this inhibition was reversible upon reoxygenation, the recovery was delayed, requiring at least 2 hours of exposure to 21% oxygen to reestablish prostanoid production. Reoxygenation also caused lipid peroxidation as measured by an increase in malondialdehyde levels. When reoxygenation was done in the presence of exogenous arachidonate, recovery of PGI2 production was complete by 1 hour. Reoxygenation in the presence of a scavenger of reactive oxygen species (Tiron) or catalase significantly improved the recovery rate of PGI2 production.

CONCLUSIONS

These results show that reoxygenation of hypoxic tissue generates oxidative stress that interferes with the recovery of prostanoid production by alteration of a biosynthetic point(s) upstream from prostaglandin H synthase (PGHS) including, at least, phospholipid peroxidation.

Central nervous system distribution of fibroblast growth factor injected into the blood stream

It has been shown that fibroblast growth factors (FGFs) protect hypocampal CAI cells from the effects of transient ischemia when injected either intraventrically or intravenously. The effectiveness of the systemic treatment seems to suggest that FGFs cross the blood-brain barrier to some extent. The appearance of basic fibroblast growth factor (bFGF) in the rat central nervous system after systemic administration have been autoradiographically examined using a 14C uniformly labeled preparation. Our results show that, two hours after a systemic bolus administration, bFGF spots in several populations of neuronal and in non-neural cells except in glial cells. Label accumulation was imperceptible when either 14C-bFGF was heated previously to the systemic injection or was co-administered with an excess of unlabeled bFGF. Our results indicate the existence of a saturable transport system of FGFs across the blood-brain barrier.

Analgesic effects of fibroblast growth factor in the rat

Intraperitoneal (i.p.) injection of acidic fibroblast growth factor (aFGF) to Sprague-Dawley rats induced short-lasting analgesia as measured by tail-flick latency (TFL) test. The maximum effect, a 26% increase in tail-flick latency, was obtained 15 min following 1 microgram i.p. aFGF. By 30 min the effect was considerably reduced, and was no longer present by 45 min after treatment. Administration of heat-inactivated aFGF or a hybrid form of aFGF (CLYT/aFGF) that, although active, is unable to cross the blood-brain barrier (BBB), caused no analgesia. Furthermore, the analgesic effects of aFGF were prevented by pretreatment with the nitric oxide synthase inhibitor, L-NG-nitroarginine methyl ester (L-NAME). Our findings demonstrate an analgesic effect of FGF, which requires crossing of BBB and implicates the nitric oxide pathway.

The effect of depressing glial function in rat brain in situ on ion homeostasis, synaptic transmission, and neuron survival

The supporting role of glial cells in maintaining neurons and in ion homeostasis has been studied in situ by perfusing the gliotoxin fluorocitrate (FC) through a microdialysis fiber in the CA1 area of urethane-anesthetized rats. Extracellular direct current potential, extracellular potassium concentration ([K+]o) and amino acid levels, extracellular pH (pHo), and evoked field activity were studied. Histology verified the swelling of glial cells after 4 hr of FC treatment. Massive neuron damage was evident after 8 hr. FC dialysis caused the rapid decrease of glutamine, pHo became progressively more acid, and [K+]o moderately elevated. Orthodromic transmission was variably blocked within 30 min to 4 hr. After 4 hr, spreading depression (SD) waves that originated from the neocortex invaded hippocampal CA1, [K+]o increased to higher levels, pHo became very acid, and there were steep increases in taurine, glutamate, and GABA levels. Simultaneously, the antidromic population spike (a-PS) became depressed and eventually disappeared. When a shorter dialysis probe that spared cortex was used to sample CA1, no SD was seen, a-PS was not abolished, and ion homeostasis was altered less markedly. Repeated SD provoked in hippocampus in the absence of FC caused only mild depression of a-PS. Dialysis of high-K+ solution in healthy neocortex or hippocampus caused only slight elevation of [K+]o at distances of 200-400 microns from the dialysis membrane. After treatment with FC, similar high-K+ dialysis raised [K+]o much more. We conclude the following: (1) recurrent SD waves injure neurons if and only if glial function has failed; (2) neurons can regulate [K+]o, albeit imperfectly; (3) glia is required for the normal fine tuning of [K+]o and particularly for the recovery of pathologically elevated [K+]o; and (4) glia are required for the regulation of pHo. The similarities between glial poisoning by FC and the reported changes in the penumbra of ischemic infarcts suggest that the extension of neuron loss into the penumbral region might depend on failure of glial protection.

Antiepileptic effects of acidic fibroblast growth factor examined in kainic acid-mediated seizures in the rat

The possibility that exogenous recombinant human acidic fibroblast growth factor (rhaFGF) may have anticonvulsant properties was investigated in a model of temporal lobe epilepsy in awake rats. We found that after intraperitoneal injection of rhaFGF in kainic acid-treated rats, tonic-clonic convulsions and mortality were decreased by 74% and 77%, respectively. These results are consistent with previous studies showing a neuroprotective effect of FGF against insults to the brain and support a possible therapeutic role for FGF in the treatment of excitotoxic processes.

Acidic fibroblast growth factor prevents death of spinal cord motoneurons in newborn rats after nerve section

The death of spinal axotomised motoneurons provides a useful tool for studying neurotrophic factors which could prevent motoneuron loss in vivo. Median and ulnar nerves of newborn rats were unilaterally sectioned and topically treated with either a vehicle solution or acidic fibroblast growth factor (aFGF). aFGF treatment increased the survival of the median and ulnar spinal motoneurons, after 7 days of axotomy, from 37% to 63%. These results show that aFGF is a neurotrophic factor for newborn spinal motoneurons, and suggest that this protein is a potential therapeutic agent for preventing the death of damaged motoneurons.

Acidic fibroblast growth factor prevents post-axotomy neuronal death of the newborn rat facial nerve

The death of facial motoneurons after axotomy provides a useful tool for studying neurotrophic factors which could prevent motoneuron loss in vivo. The right facial nerve trunk before the postauricular nerve branching of newborn rats was transected at its extracranial exit, and topically treated, at the axotomy site, with either a vehicle solution containing agarose or sucralfate, or acidic fibroblast growth factor (aFGF). Acidic FGF treatment increased the survival of the facial motoneurons from 18% to 70%. These results suggest that aFGF is a neurotrophic factor for motoneurons in vivo and that this growth factor may provide a new basis for the development of treatments to prevent the loss of damaged motoneurons.

Ischemia and reperfusion reduce the endogenous basic fibroblast growth factor (bF GF) in rat skeletal muscles

Polyclonal antibodies directed against human recombinant basic fibroblast growth factor (bFGF) were used in immunohistochemical studies to localize this growth factor in normal and wounded rat skeletal muscles. bFGF immunoreactivity was found mainly in the extracellular matrix, primarily in the endomysium, including the heparin-containing basal lamina and also in the capillary basal membrane of both normal and wounded muscles, however the signal intensity was much stronger in normal muscles. After 4-hour ischemia, about 40% of skeletal muscle fibers lost their bFGF immunoreactivity. Muscles which experienced 4-hour ischemia and 24 reperfusion had only a weaker bFGF immunoreactivity. The pathological results supported the concept of destroyed cell connection and fiber necrosis in ischemia and reperfused muscles. The mechanisms involved in this reduced concentration of bFGF in wounded muscles included oxygen radical activation, inflammatory response and reduced secretion of endogenous bFGF. These results were only partially compatible with the established mitogenic role of this protein and suggested that a reduction of endogenous FGF may partly contribute to a delay in wound healing.

Acidic fibroblast growth factor reduces rat skeletal muscle damage caused by ischemia and reperfusion

Acute interruption of arterial blood flow to the extremities is often associated with significant morbidity and mortality. Broad-spectrum mitogenic and non-mitogenic activities of FGFs inspired us to study its protecting effects on tissue injuries in ischemia reperfusion condition. We found that systemic administration of aFGF after reperfusion onset prevented severe skeletal muscle injuries. In rats treated with aFGF, the tissue edema was reduced significantly, the tissue viability was increased, and the muscle fibers contained more succinate dehydrogenase (SDH) and adenosine triphosphatase (ATPase). The pathological results supported the concept of improved prevention with aFGF treatment. The possible tissue protection by aFGF may come from its ability to regulate the concentration of extra- and intracellular calcium ion. Besides, it may moderate other Ca2+ dependent enzyme conversion processes. Also, it may take part in the vascular tone regulation under ischemia and reperfusion conditions. These results suggest further study of tissue ischemia prevention with FGF and its possible mechanisms in the future.

Neuroprotective effect of acidic fibroblast growth factor on seizure-associated brain damage

The neuroprotective effect of acidic fibroblast growth factor (aFGF) has been analysed in a rat model of seizures-associated brain damage. We report that after treatment with a convulsivant dose of Kainic acid, systemically administered aFGF prevents neuronal degeneration in specific brain areas, mainly in the hippocampal formation. Our findings extend the potential pharmacological use of fibroblast growth factors and afford new data to understand the neurophysiology of these proteins.

Fibroblast growth factors, proteins with a broad spectrum of biological activities

The first two members of the fibroblast growth factor family of proteins were isolated ten years ago. The family now includes nine members. Six of them are biologically and structurally closely related, and often the denomination fibroblast growth factor family refers exclusively to them. It has become progressively evident that the six most similar members of the family induce mitogenesis in practically all mesoderm and neuroectoderm derived cells. In healthy animals only two of these six polypeptides have been detected, which are currently known as acidic and basic fibroblast growth factors, respectively. These two polypeptides are widely distributed in the organism. Evidence has been progressively accumulating that acidic and basic fibroblast growth factors show too, a wide assortment of hormone-like activities.

Immunohistochemical localization of basic fibroblast growth factor in choroid plexus of the rat

In the present study, we report that an intense bFGF-immunoreactivity has been detected in the choroid plexus of the brain ventricles of adult rats. These results suggest that epithelial choroid plexus cells may be the source of the cerebrospinal fluid bFGF.

Fibroblast growth factor and cerebral ischaemia

Although the cellular events that accompany brain injury have been well characterized, the factors that mediate growth and repair in the central nervous system (CNS) are only beginning to be identified. One such is fibroblast growth factor. The fibroblast growth factor (FGF) family of proteins includes, at this moment, seven structurally related polypeptides. Acidic and basic FGF (aFGF and bFGF) were the first described members of the family, and are the best characterized. Both proteins bind with high affinity to the same kind of receptor at the plasma membrane through which they induce a whole series of intracellular events that mediate their physiological functions. FGF, which displays pleiotrophic biological activities including mitogenesis, chemotaxis, and induction of differentiation is a potent angiogenic factor in vivo, tested in assays as different as the rabbit cornea, the chick chorioalantoic membrane (CAM), the rat common carotid artery, and the rat brain.

Nitrergic innervation of rat brain vasculature

Nitric oxide synthase has been located in the brain, in several neuronal populations which appear in close contact either with the microvasculature or the external surface of extracerebral vessels. These data provide structural support to the pharmacological evidences of the nitric oxide participation in the regulation of vascular tone of brain blood vessels.

Single topical application of human recombinant basic fibroblast growth factor (rbFGF) promotes neovascularization in rat cerebral cortex

Basic fibroblast growth factor (bFGF) is a morphogenic, chemotactic, mitogenic, and angiogenic peptide found within the central nervous system (CNS) with potent neurotrophic effects. A potential role in ischemia-induced vascular growth has been suggested for bFGF. In this study, we show that single, topical administration of human recombinant basic fibroblast growth factor (rbFGF) in the rat cerebral cortex promotes capillary overgrowth and might mimic the angiogenic response observed after brain ischemia. The implication of this finding for the therapeutic use of basic FGF in angiogenic therapy is discussed.

Single-step purification on DEAE-sephacel of recombinant polypeptides produced in Escherichia coli

We describe a method for the purification of recombinant proteins based upon the selective interaction of the choline-binding domain of the pneumococcal murein hydrolase and tertiary amines. Proteins of interest, fused to the binding domain by a peptide linker, containing the cleaving sequence recognized by blood coagulation factor Xa, can either be assayed for biological activities in vitro and in vivo or have the binding moiety removed to yield a totally unmodified form, suitable for clinical and functional studies. The method can also be applied to the production of low molecular mass peptides. The principle of the technique is illustrated with acidic fibroblast growth factor and with a neuropeptide-like fragment of ten amino acids contained within its sequence.

Fibroblast growth factor injected in cerebral ventricles does not decrease mean arterial blood pressure

Intracerebroventricular injections of acidic fibroblast growth factor (aFGF) in rats did not elicit any change in the mean arterial blood pressure, and also did not appreciably affect the hypotensive effect of intravenous injections of aFGF. These observations are of general clinical interest, since such effects could constitute important drawbacks for the therapeutic applications of FGF.

Hypotensive activity of fibroblast growth factor

Acidic and basic fibroblast growth factors (FGFs) are members of a family of proteins that are broad-spectrum mitogens, have diverse hormone-like activities, and function in tumorigenesis. FGF's ability to raise the concentration of intracellular calcium ion suggests that FGF could induce the synthesis of endothelium-derived relaxing factor (EDRF) and consequently vasodilation. Systemic administration of FGF decreased arterial blood pressure. This effect was mediated by EDRF and by adenosine triphosphate-sensitive potassium ion channels. The hypotensive effect of FGF was segregated from its mitogenic activity by protein engineering. These results extend the range of FGF autocrine activities and potential therapeutic applications, emphasize the role of endothelium as an arterial blood pressure--regulating organ, and provide insight on the structural basis of FGF functions.

Vascular response to basic fibroblast growth factor when infused onto the normal adventitia or into the injured media of the rat carotid artery

Immunohistochemical techniques localize basic fibroblast growth factor (FGF) in endothelial and smooth muscle cells of the common carotid artery. Thus, we studied the effect in rats of basic FGF infused for 14 days onto the adventitia or into the media in vivo. In untreated rats, the adventitial layer is uniform, and few vessels are observed in cross sections (mean +/- SEM is 0.351 +/- 0.16 capillaries/field at a magnification of x 480). Whereas saline infusion increases the mean number of vasa vasorum to 2.73 +/- 0.011 capillaries/field (p less than 0.01), basic FGF (1 ng/microliter/hr) increases the capillary number to 13.4 +/- 0.67 capillaries/field. The effects are local and restricted to the site of delivery; no cell proliferation is observed even 2 mm from the site of infusion. There is also no evidence of the infiltration of macrophages and monocytes. In an effort to determine the effect of basic FGF in the media, a small longitudinal (1-mm) incision was made in the adventitia, and saline or basic FGF (1 ng/microliter/hr) was infused for 14 days into the arterial wall. Under these conditions, basic FGF is a potent inducer of smooth muscle cell proliferation in the vascular wall as well as of new capillaries. In these instances, however, the capillaries formed are thick-walled. The results support the hypothesis that basic FGF may be contributing to the growth and maintenance of the vasa vasorum and of vascular smooth muscle cells.

Expression of basic fibroblast growth factor and its receptor in the rat subfornical organ

Basic fibroblast growth factor (FGF), its mRNA and the mRNA that encodes for its receptor have all been localized in the rat subfornical organ (SFO). Basic FGF is widely distributed throughout the SFO; it is present in neurons, in the vascular basement membrane of lateral blood vessels (but not those within the SFO) and in ependymal cells surrounding the SFO. Results of in situ hybridization show that the expression of basic FGF mRNA is detected throughout the organ. Similarly, the expression of flg, the gene for the putative basic FGF receptor, can also be detected in the SFO. The results all support the possibility that this growth factor may modulate the known physiological functions of the SFO.

Immunohistochemical localization of basic fibroblast growth factor in ependymal cells of the rat lateral and third ventricles

The presence of basic fibroblast growth factor (bFGF) in the third and the lateral ventricular ependyma of the rat has been investigated under the light microscope using a polyclonal antibody against bFGF, through the unlabelled peroxidase-antiperoxidase procedure; bFGF-immunoreactivity (bFGF-IR) is observed in the entire ependymal cell layer of ventricles. Also ependymal tanycytes within the inferior portion of the wall and floor of the third ventricle show bFGF-IR. Tanycytic processes are in close contact with hypothalamic capillaries. The present study strongly suggests that brain ependymal bFGF plays unidentified roles unrelated to its angiogenic or mitogenic capacities.

Ischemic reperfusion injury in rabbit spinal cord: protective effect of superoxide dismutase on neurological recovery and spinal infarction

The potential role of superoxide dismutase (SOD), a specific superoxide anion radical scavenger, in treating spinal cord ischemia was investigated in rabbits subjected to aortic occlusion for 20 min. SOD treatment, targeted to the early reperfusion period, reduced both motor dysfunction and incidence of spinal infarcts at 7 days after ischemia. Present results suggest that oxygen-derived free radicals play a role in the pathogenesis of infarcts developing in the spinal cord after ischemia and reperfusion injuries.

Administration of bovine superoxide dismutase prevents sequelae of spinal cord ischemia in the rabbit

The contribution of free radical-mediated reperfusion injury to the ischemic damage caused by total arterial occlusion has been investigated in a model of transient spinal cord ischemia in the rabbit. Spinal cord ischemia was produced in 20 anaesthetized rabbits by temporary luminal occlusion (20 min) of the abdominal aorta below the renal arteries. Superoxide dismutase (5 mg/kg) (10 animals) was infused before and during reperfusion below aortic occlusion using an infusion pump that infused the enzyme through the contralateral femoral artery. Control (10 animals) received sterile saline with the same procedure. In this later group, 4 animals developed paraplegia, 4 were paretic and only 2 were normal. However, in the treated group, 6 animals were normal while 3 were paretic and only one appeared paralyzed. We conclude that: a) oxygen free radicals generated during reperfusion are involved in producing the ischemic injury, and b) the ischemic spinal cord injury is prevented by superoxide dismutase.

Basic fibroblast growth factor (FGF) promotes cartilage repair in vivo

Although it has been clearly established that basic fibroblast growth factor (FGF) is a potent mitogen for chondrocytes in vitro, there is little evidence that it can stimulate this cell type in vivo. In an effort to address this problem, we examined the effect of an intraarticular administration of basic FGF. Alzet osmotic pumps delivering the mitogen to the site of injury promotes the healing of intra-chondrial lesions by stimulating chondrocyte proliferation and the formation of extracellular matrix. The observation that chronic infusions of basic FGF can elicit a repair response at the site of injury suggests that this growth factor may have therapeutic applications that extend beyond its capacity to induce neovascularization. The results also suggest that one of the ways that the perichondrium mediates cartilage repair may be by the local production of FGF-like mitogens.

Freeze-fracture cytochemistry of cholesterol content in neuronal plasma membrane following cerebral ischaemia

Minor changes on the neuronal perikaryon cytoplasm and large alterations in neuronal processes have been demonstrated with transmission electron microscopy after 60 minutes of focal and selective cerebral ischaemia. The distribution of cholesterol in neuronal plasma membrane and perikarya plasmalemma of normal and ischaemic caudate nucleus was investigated with the polyene antibiotic filipin, a morphological probe for membrane cholesterol domains in freeze-fracture replicas. After filipin incubation of prefixed vibratome slices, filipin-cholesterol complexes appeared as 20-30 proturberances and pits on P- and E-faces. Distinct patterns of filipin-cholesterol complexes were found in non-ischaemic and ischaemic neuronal membrane. The filipin-treated specimens showed a 35-40% drop in cholesterol content in the neuronal plasmalemma one hour after cerebral ischaemia.

An in vivo model for study of the angiogenic effects of basic fibroblast growth factor

We have investigated the angiogenic effects of basic fibroblast growth factor following its implantation in slow release beads under the kidney capsule. The presence of basic fibroblast growth factor in the subcapsular space induced a marked angiogenic response maximal at 1 microgram dose per kidney. Histological examination at the site of treatment failed to reveal evidence of an inflammatory response, thus supporting the observation that basic fibroblast growth factor alone can stimulate in vivo neovascularization. Beads pretreated with saline or with human growth hormone had no angiogenic effect. Because of the readily accessible location in the retroperitoneal space, the ease of drug delivery, and the marked vascular proliferation seen in response to FGF, our results suggest that the kidney capsule is an excellent model for study of the physiological role played by FGF and related peptides in promoting angiogenesis in vivo.

Adrenergic innervation of human middle cerebral artery. Ultrastructural observations

The innervation of the human middle cerebral artery is studied with transmission electron microscopy using the chromaffin reaction technique. Adrenergic nerve fibers and related terminals, with granular electrodense neurotransmitter vesicles, are confined to the tunica adventitia-tunica media transitional zone and the outer layers of the media. These findings may indicate the presence of an adrenergic vasoconstrictor system for circulation control in the human middle cerebral artery.

Intramembranous cytochemistry: a new morphological technique for studying cholesterol in the astrocyte plasma membrane of ischemic brain cells

The distribution of cholesterol in the astrocytic plasma membranes of normal and ischemic caudate nucleus in the cat was investigated with the polyene antibiotic, filipin, a morphological probe for membrane cholesterol domains in freeze-fracture tissue replicas. After filipin incubation of prefixed vibratome slices, filipin-cholesterol complexes appeared as 20 to 30 nm protuberances and pits on P- and E-faces of the replicas. Distinct patterns of filipin-cholesterol complexes were found on nonischemic and ischemic astrocyte membranes. The filipin-treated specimens showed an 80% decrease in astroglial plasmalemma of cholesterol 1 hour after cerebral ischemia.

Immunohistochemical detection of inhibin in the gonad

Antiserum to inhibin was produced in rabbits by immunization with a synthetic [Tyr30]alpha-chain(1-30)NH2 fragment of porcine inhibin coupled to bovine serum albumin, and the elicited antiserum was used in conjunction with the avidin-biotin immunoperoxidase procedure to localize inhibin-reactive cells in various rat tissue preparations. In the testes, only the Sertoli cells revealed immunoreactivity with the antiserum. Intense staining was also observed in ovarian follicular granulosa cells but not in the theca layer outside the basement membrane. In addition, the luteal cells in the corpus luteum were also stained by the antiserum. The positive staining in the gonadal tissues could be blocked completely by pre-adsorbing the serum with either the synthetic peptide or native inhibin. Immunostaining was not detected in brain, pituitary, thymus, stomach, pancreas, kidney and adrenal section, thus confirming that inhibin is a polypeptide originating only from specific cells of the gonad.

Lack of effect of compound 48/80 on human umbilical vein endothelium

Human umbilical veins have been treated with compound 48/80, a histamine liberator factor, in order to obtain information about the histamine content in the Weibel-Palade bodies. Ultrastructural observations show a lack of effect in the morphology of this organelle. Our findings suggest that the Weibel-Palade bodies are not histamine storage organelles in human umbilical vein.

Disturbance of plasmalemmal astrocytic assemblies in focal and selective cerebral ischemia

Selective cerebral ischemia was induced in the caudate nucleus of seven normothermic anesthetized cats through transorbital clamping of the anterolateral penetrating lenticulostriated arteries. The plasmalemma of astrocytic foot processes has been studied with the freeze-fracture technique and conventional electron microscopy 10, 15 and 30 min after ischemia. After 15 min of circulatory arrest, assemblies of intramembrane particles (IMPs) disappear in some areas of astroglial perivascular plasmalemma in the ischemic caudate nucleus. Interastrocytic gap junctions do not change significantly. 30 min after ischemia, the pericapillary astroglial end foot is expanded and organelles are greatly perturbed (cytotoxic edema). Although the function of astrocytic intramembrane particle assemblies is unclear, it is postulated that the disappearance of this membrane specialization may play a role in the pathophysiology of cytotoxic astroglial edema.

Quantitative electron microscopic study of calcium accumulation in cerebral ischemia mitochondria

Formation of calcium deposits in mitochondria is a consistent feature of irreversible injury in ischemic myocardium. We studied calcium accumulation in nerve cell mitochondria in a cat model 30 and 60 minutes after cerebral ischemia localized in the anterior part of the caudate nucleus and adjacent internal capsule. In control animals, calcium deposits were visible in synaptic vesicles, Golgi apparatus, mitochondria, lysosomes, and in glial and neuronal nuclei. After cerebral ischemia, findings included astrocytic swelling and degeneration of neurons, with an increase in calcium pyroantimoniate mitochondrial deposits. Content of intramitochondrial calcium deposits is related to duration of ischemia as well as the amount of cellular lesions.

Absence of filipin-sterol complexes from the ciliary necklace of ependymal cells

The polyene antibiotic filipin reacts specifically with membrane cholesterol and produces membrane perturbations. Prefixed vibratome slices of cat ependymal cells were treated with a glutaraldehyde solution containing 300 microM filipin. Freeze-fracture of these cells revealed numerous 25-30 nm protuberances on fracture faces (filipin-sterol complexes) in the ciliary membrane. In the ciliary necklace, however, these filipin-sterol complexes were absent. These results suggest that the ciliary necklace has a low cholesterol content.

Possible role of endothelium in the orientation of smooth muscle cells in experimental neointima

Myointimal cells (MIC) orientation and intimal thickening evolution, induced by grafting an autogenous venous patch onto the rat common carotid artery, were studied with light microscopy at different times until 14 months after surgery. Intimal thickenings in the venous patch were most prominent at an intermediate postoperative period, after which their mean size did not change significantly. In host artery neointima, the greatest MIC proliferation was observed at a late stage of evolution. MIC arrangement was predominantly circumferential to the blood stream in venous patch neointima, whereas it was mostly axial in the host artery. The interaction between MIC orientation and endothelial regeneration in the operated vessel is discussed.