Kazuhide Yoshida

Nitric oxide synthase-immunoreactive nerve fibers in dog cerebral and peripheral arteries

Nitric oxide synthase (NOS)-immunoreactive fibers innervating the dog arterial wall were histochemically determined by the use of NOS antiserum. NOS-immunoreactive fibers were consistently found in every arterial wall examined. In a whole-mount preparation, NOS-positive fibers were detectable in the small pial artery having a diameter of about 100 microns as well as the proximal middle cerebral artery. Further detailed analyses in thin cryostat sections indicated that in middle cerebral, basilar, temporal, mesenteric and femoral arteries, fine NOS-positive fibers were detected in outer zones of the media in addition to many thicker fibers in the adventitia. However, in the coronary artery, many thick fibers were situated in the adventitia, and fine NOS-positive fibers were not found in the media. Injection of ethanol to the pterygopalatine ganglion markedly decreased or abolished the NOS immunoreactivity in nerve cells and fibers and abolished the innervation of NOS-positive fibers in the wall of middle cerebral artery of the ipsilateral side. Together with findings in our previous publications concerning the functional role of nitroxidergic nerve in the control of arterial tone, we conclude that perivascular nerves containing NOS are crucial in eliciting the neurally induced, NO-mediated arterial relaxation.

Impairment by damage of the pterygopalatine ganglion of nitroxidergic vasodilator nerve function in canine cerebral and retinal arteries.

Histochemical study revealed that transcutaneous injection of ethanol into the vicinity of the pterygopalatine ganglion greatly decreased the positive staining for NADPH diaphorase activity after 1 week in the ipsilateral ganglion of a dog and abolished the staining of perivascular nerves in the middle and posterior cerebral arteries. Transmural electrical stimulation or nicotine produced a relaxation in middle and posterior cerebral arteries isolated from the side with the nontreated ganglion (control side), whereas the relaxation was abolished or reversed to a contraction in the arteries from the side with the ethanol-treated ganglion. Nitric oxide-induced relaxations did not differ in the arteries from both sides. The response to nerve stimulation of the control arteries was suppressed by treatment with NG-nitro-L-arginine (L-NA), an inhibitor of nitric oxide synthase, and the inhibition was reversed by L-arginine. Nicotine produced a contraction followed by a relaxation in central retinal arterial strips obtained from the control side; the relaxation was abolished and the contraction was potentiated in the arteries from the treated side. The nicotine-induced relaxation was abolished by L-NA, and the contraction was suppressed by phentolamine. On the other hand, the nicotine-induced relaxation in superficial temporal arteries, susceptible to L-NA, was not attenuated by treatment with ethanol. The findings obtained so far support our hypothesis that nitric oxide released from the vasodilator nerve acts as a transmitter to produce arterial smooth muscle relaxation and suggest that the nerve fibers to the cerebral and retinal arteries arise from the pterygopalatine ganglion.

Analysis of the potentiating action of NG-nitro-l-arginine on the contraction of the dog temporal artery elicited by transmural stimulation of noradrenergic nerves

SummaryDog temporal artery strips without endothelium responded to transmural electrical stimulation with a contraction which was potentiated by NG-nitro-l-arginine (l-NNA). The noradrenaline-induced contraction and the release of 3H-noradrenaline were not affected. The stimulation-induced contraction was reversed to a relaxation by phentolamine. The relaxation was not influenced by timolol and atropine but inhibited by l-NNA; l-arginine abolished the inhibition. Transmural stimulation released NOx from the arteries, the release being abolished by l-NNA. Potentiation by l-NNA of the neurally-induced contraction appears to be due to elimination of NO produced by non-adrenergic, non-cholinergic vasodilator nerve activation.

Nitroxidergic Innervation in Dog and Monkey Renal Arteries

We analyzed mechanisms underlying neurogenic vasodilatation in dog and Japanese monkey renal arteries. Isometric mechanical responses of the arterial strip to nerve stimulation by nicotine were recorded. Nicotine-induced contractions were abolished by hexamethonium and potentiated by NG-nitro-L-arginine, a nitric oxide synthase inhibitor. The potentiating effect was reversed by L-arginine. NG-Nitro-L-arginine did not potentiate the contraction caused by norepinephrine. The nicotine-induced contraction was reversed to a relaxation by prazosin. The relaxation was not influenced by indomethacin, timolol, or atropine but was abolished by NG-nitro-L-arginine, methylene blue (a guanylate cyclase inhibitor), oxyhemoglobin (a nitric oxide scavenger), and hexamethonium. In the strips treated with NG-nitro-L-arginine, the nicotine-induced relaxation was restored by L-arginine. Histochemical study demonstrated perivascular nerves containing NADPH diaphorase and nitric oxide synthase immunoreactivity in dog and monkey arteries. We conclude that renal arteries are innervated by nitric oxide-mediated vasodilator and adrenergic vasoconstrictor nerves, and depression of the vasodilator nerve function by nitric oxide synthase inhibition potentiates the contraction caused by adrenergic nerve excitation.

NADPH diaphorase-positive neurons in the intracardiac plexus of human, monkey and canine right atria.

Distribution of nitric oxide synthase in intracardiac ganglion cells located in human, monkey and canine right atria was histologically investigated using the reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase method and acetylcholinesterase histochemistry. In the intracardiac ganglion, many large neurons exhibited both positive reactions, whereas some of the NADPH diaphorase-positive small neuronal cells were shown with negative acetylcholinesterase reaction.

Involvement of Nitroxidergic and Noradrenergic Nerves in the Relaxation of Dog and Monkey Temporal Veins

We determined involvement of nitric oxide (NO) derived from perivascular nerve in venous relaxation. In helical strips of dog superficial temporal veins contracted with prostaglandin F2α (PGF2α) nicotine produced a contraction, which was reversed to a relaxation by prazosin. The relaxation was partially attenuated by timolol or metoprolol. The residual relaxation was not influenced by treatment with atropine or indomethacin and by endothelium denudation but was abolished by NG-nitro-L-arginine (L-NA), a NO synthase inhibitor, and hexamethonium. L- but not D-arginine reversed the inhibition induced by L-NA. Relaxations induced by NO were not influenced by L-NA. Similar results were also obtained in relaxations induced by transmural electrical stimulation that were sensitive to tetrodotoxin (TTX). In the monkey venous strips, relaxations induced by nicotine under treatment with prazosin were reduced by timolol. The relaxation observed with combined treatment with α- and β-antagonists was abolished by L-NA, and L-arginine restored the response. The presence of nerve fibers containing NO synthase immunoreactivity or NADPH diaphorase in the adventitia of dog and monkey veins was determined histologically. The findings so far obtained strongly suggest the presence of perivascular nerves that mediate venodilation via a release of NO. Contractions of the temporal vein appear to be mediated by norepinephrine (NE) released from adrenergic nerves that stimulates α1-adrenoceptors, whereas relaxations are mediated by neurogenic NE, acting possibly on the β1-adrenoceptor subtype, in addition to NO derived from nerves.

Distribution of NADPH diaphorase-reactive nerves in the human female genital organ.

Objective. This study was designed to histochemically clarify the presence of nerves containing NADPH diaphorase, representing the catalytic activity of nitric oxide synthase, in the human female genital organ.

Colocalization of acetylcholinesterase and vasoactive intestinal peptide (VIP) in nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) positive neurons in the intralingual ganglia and perivascular nerve fibers around lingual arteries in the porcine, monkey and canine tongue

Distribution of nitric oxide synthase in the intrinsic ganglia in the porcine, monkey and canine tongue was histologically investigated using the reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) method, acetylcholinesterase histochemistry and vasoactive intestinal peptide (VIP) immunohistochemistry. The majority of intralingual ganglionic cells showed intense NADPH-d reactivity with positive acetylcholinesterase reaction or positive VIP immunohistochemistry. The NADPH-d positive, acetylcholinesterase-rich and the NADPH-d positive, VIP immunoreactive nerve fibers are particularly conspicuous around intralingual blood vessels. These fibers around the arteries in the tongue may be partly derived from the intralingual ganglion cells, because some bundles associated with these nerve cells were easily traced on the wall of blood vessels. The present study suggests the view that the three markers coexist in the axons and nerve terminals of these intralingual neurons.

AE0047, a new dihydropyridine Ca2+ entry blocker, inhibits the responses to adrenergic nerve stimulation and substance P in dog mesenteric arteries

AE0047, a new dihydropyridine-type Ca2+ entry blocker, significantly inhibited the contractions induced by transmural electrical stimulation and norepinephrine in dog mesenteric artery strips. The inhibition was greater in the case of the response to nerve stimulation. The 3H-overflow ratio evoked by electrical stimulation from strips previously soaked in [3H]norepinephrine was significantly reduced by AE0047 but not by nicardipine in a concentration sufficient to attenuate the response to norepinephrine. In aorta homogenate preparations, [3H]bunazosin binding was not replaced by AE0047 but by phentolamine. In strips treated with indomethacin, the endothelium-dependent relaxation caused by substance P and bradykinin was attenuated by treatment with AE0047 but not with nicardipine. The nitric oxide (NO)-induced relaxation was not influenced by AE0047. Cyclic GMP levels in the artery strips increased in response to substance P; the increase was markedly suppressed by AE0047 but not by nicardipine. In contrast to nicardipine, AE0047 appeared to inhibit the release of norepinephrine from adrenergic nerves and of NO from endothelial cells. The inhibition may be associated with the decreased transmembrane influx of Ca2+ in these tissues.

Potentiation by hypoxia of contractions caused by angiotensin II in dog and monkey cerebral arteries.

Background and Purpose Hypoxia alters the responsiveness to endogenous substances of cerebral arteries, possibly resulting in the modulation of blood supply to ischemic brain regions. The present study was undertaken to analyze the mechanism of potentiation by hypoxia of angiotensin II-induced cerebroarterial contractions. Methods Monkey and dog cerebral arterial strips with endothelium were suspended for isometric tension recording in Ringer-Locke solution aerated with 95% O2-5% CO2 (partial O2 pressure, 570-600 mm Hg) or 95% N2-5% CO2 (approximately 10 mm Hg). Results Contractions induced by angiotensin II and substance P were potentiated by exposure to hypoxia, whereas contractile responses to prostaglandin F2α were not influenced. Treatment with cyclooxygenase inhibitors abolished the peptide-induced contraction but did not alter the prostaglandin F2α-induced contraction. Relaxations induced by arachidonic acid were suppressed by indomethacin and hypoxia, whereas those caused by a prostaglandin I2 analogue were unaffected. Conclusions The potentiation by hypoxia of cerebroarterial contractions caused by angiotensin II and substance P appears to be due to an interference with the synthesis of prostaglandin I2 from arachidonic acid and a resultant increase in the production of vasoconstrictor prostaglandins.