Capsaicin- resistant arterial baroreceptors

BACKGROUND: Aortic baroreceptors (BRs) comprise a class of cranial afferents arising from major arteries closest to the heart whose axons form the aortic depressor nerve. BRs are mechanoreceptors that are largely devoted to cardiovascular autonomic reflexes. Such cranial afferents have either lightly myelinated (A-type) or non-myelinated (C-type) axons and share remarkable cellular similarities to spinal primary afferent neurons. Our goal was to test whether vanilloid receptor (TRPV1) agonists, capsaicin (CAP) and resiniferatoxin (RTX), altered the pressure-discharge properties of peripheral aortic BRs. RESULTS: Periaxonal application of 1 μM CAP decreased the amplitude of the C-wave in the compound action potential conducting at <1 m/sec along the aortic depressor nerve. 10 μM CAP eliminated the C-wave while leaving intact the A-wave conducting in the A-δ range (<12 m/sec). These whole nerve results suggest that TRPV1 receptors are expressed along the axons of C- but not A-conducting BR axons. In an aortic arch – aortic nerve preparation, intralumenal perfusion with 1 μM CAP had no effect on the pressure-discharge relations of regularly discharging, single fiber BRs (A-type) – including the pressure threshold, sensitivity, frequency at threshold, or maximum discharge frequency (n = 8, p > 0.50) but completely inhibited discharge of an irregularly discharging BR (C-type). CAP at high concentrations (10–100 μM) depressed BR sensitivity in regularly discharging BRs, an effect attributed to non-specific actions. RTX (≤ 10 μM) did not affect the discharge properties of regularly discharging BRs (n = 7, p > 0.18). A CAP-sensitive BR had significantly lower discharge regularity expressed as the coefficient of variation than the CAP-resistant fibers (p < 0.002). CONCLUSION: We conclude that functional TRPV1 channels are present in C-type but not A-type (A-δ) myelinated aortic arch BRs. CAP has nonspecific inhibitory actions that are unlikely to be related to TRV1 binding since such effects were absent with the highly specific TRPV1 agonist RTX. Thus, CAP must be used with caution at very high concentrations

The Cardiovascular System

We establish the existence of an entire solution for a class of stationary Schrodinger systems with subcritical discontinuous nonlinearities and lower bounded potentials that blow‐up at infinity. The proof is based on the critical point theory in the sense of Clarke and we apply the Mountain Pass Lemma for locally Lipschitz functionals. Our result generalizes in a nonsmooth framework the result of Rabinowitz [16] on the existence of entire solutions of the nonlinear Schrodinger equation. First Published Online: 14 Oct 201

Vertebral artery anomaly with entry at C4—avoiding a surgical pitfall: a case report

We present a case of an unusual course of the vertebral artery (VA) with intra-foraminal entrance at C4. A patient with traumatic fracture of C3 and C4 with dislocation C3/C4, spinal cord compression and ensuing quadriplegia presented with unilateral entrance of the VA at C4 detected on preoperative magnetic resonance imaging (MRI). The patient was surgically decompressed and stabilized by an anterior-posterior approach without intra-operative complications. Apart from anatomical findings no clinical case of entrance of the VA at C4 had been described in recent clinical literature. A physiologic high entrance of the VA is very rare but must be diagnosed preoperatively to avoid potential life threatening complications

Serial heart rate changes in rats inoculated by conjunctival instillation of Trypanosoma cruzi obtained from bug faeces Alterações do ritmo cardíaco de ratos infectados pela via conjuntival por Trypanosoma cruzi obtidos de fezes de triatomíneos

The cardiac effects of experimentally induced myocarditis, when the parasite is obtained from mouse blood, are well known. However, the consequences of the infection when the parasites are obtained from bug faeces are less well defined. In the present investigation, we have used the "Y" strain of Trypanosoma cruzi, which was maintained in Rhodnius prolixus by repeated passages in mice. The faeces of 30 infected bugs were collected, the number of parasites counted and 4,000 parasites inoculated by the conjunctival route in 60 rats. Twenty-nine other rats received faeces from noninfected bugs (sham-inoculated controls) and 40 were used as normal controls. The heart rate of the three groups of animals was recorded under general anesthesia with ether. The heart rate, at day 0 pre-inoculation, was similar in the three groups of animals (Controls: 379 ± 27 beats/min Mean ± SD; Sham-inoculated: 366 ± 31; Infected: 351 ± 29) (p> 0.05). In the infected animals, the mean heart rate began to increase significantly by day 12 following infection (375 ± 31), reaching the highest values between days 18 (390 ± 33) and 21 (403 ± 33) and returned to baseline by day 30 (359 ± 28) (p< 0.05). The heart rate changes were statistically different from those observed in the sham-inoculated controls and in the control animals. Therefore, these heart rate changes were provoked by the Trypanosoma cruzi-induced infection. Thus, it appears that irrespective of the source of the parasite and route of inoculation Trypanosoma cruziacute infection provokes a transient sinus tachycardia.<br>Os efeitos da miocardite chagásica experimental, produzida por Trypanosoma cruzi proveniente do sangue de camundongos são bem conhecidos. O mesmo não ocorre quando a inoculação é feita com Trypanosoma cruzi proveniente de fezes do vetor. No presente estudo, usamos a variedade "Y" do Trypanosoma cruzi mantida em Rodhnius prolixus por repetidas passagens em camundongos. As fezes de 30 insetos parasitados foram coletadas e contados os parasitas. O estudo foi desenvolvido em três grupos de ratos. O primeiro, controle, formado por 40 animais, o segundo, por 29 animais que receberam fezes de insetos não infectados (controle falso inoculado) e o terceiro grupo constituído por 60 ratos inoculados com 4.000 parasitas, por via conjuntival. Em todos os animais, após anestesia geral, registrou-se a freqüência cardíaca (FC). Esta, antes da inoculação, era similar nos infectados e nos controles (controle 379 ± 27bpm; falso inoculado: 366 ± 31bpm; infectado 351 ± 29bpm). No 12º dia após a infecção, a FC no grupo chagásico começou a se elevar (375 ± 31bpm) atingindo seu valor máximo entre os dias 18 (390 ± 33bpm) e 21 (403 ± 33bpm). No 33º dia pós-infecção, a FC retornou ao valor basal inicial. Nos grupos controles, não se detectaram alterações da FC. O estudo estatístico mostrou que as variações da FC, no grupo infectado, foram estatisticamente diferentes das detectadas nos outros grupos. Conclui-se que a infecção pelo Trypanosoma cruzi, em ratos, produz taquicardia sinusal transitória, independente da fonte do parasita e da via de inoculação