Modulation of contractions to ergonovine and methylergonovine by nitric oxide and thromboxane A2 in the human coronary artery

Favorable Vasomotor Function after Drug-Coated Balloon-Only Angioplasty of De Novo Native Coronary Artery Lesions

Balloon-injured coronary segments are known to harbor abnormal vasomotion. We evaluated whether de novo coronary lesions treated using drug-coated balloon (DCB) are prone to vasospasm and how they respond to ergonovine and nitrate. Among 132 DCB angioplasty recipients followed, 89 patients underwent ergonovine provocation test at 6–9 months follow-up. Within-subject ergonovine- and nitrate-induced diameter changes were compared among three different sites: DCB-treated vs. angiographically normal vs. segment showing prominent vasoreactivity (spastic). No patient experienced clinically refractory vasospastic angina or symptom-driven revascularization during follow-up. Ergonovine induced vasospasm in seven patients; all were multifocal spasm either involving (n = 2) or rather sparing DCB-treated segments (n = 5). None showed focal spasm that exclusively involved DCB-treated lesions. Among 27 patients with vasospastic features, DCB-treated segments showed less vasoconstriction than spastic counterparts (p < 0.001). A total of 110 DCB-treated lesions were analyzed to assess vasomotor function. Vasomotor function, defined as a combined constrictor and dilator response, was comparable between DCB-treated and angiographically normal segments (p = 0.173), while significant differences were observed against spastic counterparts (p < 0.001). In our study, DCB-treated lesions were not particularly vulnerable to vasospasm and were found to have vasomotor function similar to angiographically normal segments, supporting safety of DCB-only strategy in treating de novo native coronary lesions.

5-HT1D receptors inhibit the monosynaptic stretch reflex by modulating C-fiber activity

The monosynaptic stretch reflex (MSR) plays an important role in feedback control of movement and posture but can also lead to unstable oscillations associated with tremor and clonus, especially when increased with spinal cord injury (SCI). To control the MSR and clonus after SCI, we examined how serotonin regulates the MSR in the sacrocaudal spinal cord of rats with and without a chronic spinal transection. In chronic spinal rats, numerous 5-HT receptor agonists, including zolmitriptan, methylergonovine, and 5-HT, inhibited the MSR with a potency highly correlated to their binding affinity to 5-HT_1D receptors and not other 5-HT receptors. Selective 5-HT_1D receptor antagonists blocked this agonist-induced inhibition, although antagonists alone had no action, indicating a lack of endogenous or constitutive receptor activity. In normal uninjured rats, the MSR was likewise inhibited by 5-HT, but at much higher doses, indicating a supersensitivity after SCI. This supersensitivity resulted from the loss of the serotonin transporter SERT with spinal transection, because normal and injured rats were equally sensitive to 5-HT after SERT was blocked or to agonists not transported by SERT (zolmitriptan). Immunolabeling revealed that the 5-HT_1D receptor was confined to superficial lamina of the dorsal horn, colocalized with CGRP-positive C-fibers, and eliminated by dorsal rhizotomy. 5-HT_1D receptor labeling was not found on large proprioceptive afferents or α-motoneurons of the MSR. Thus serotonergic inhibition of the MSR acts indirectly by modulating C-fiber activity, opening up new possibilities for modulating reflex function and clonus via pain-related pathways. NEW & NOTEWORTHY Brain stem-derived serotonin potently inhibits afferent transmission in the monosynaptic stretch reflex. We show that serotonin produces this inhibition exclusively via 5-HT_1D receptors, and yet these receptors are paradoxically mostly confined to C-fibers. This suggests that serotonin acts by gating of C-fiber activity, which in turn modulates afferent transmission to motoneurons. We also show that the classic supersensitivity to 5-HT after spinal cord injury results from a loss of SERT, and not 5-HT_1D receptor plasticity.

Microvascular angina: angina that predominantly affects women

In women receiving evaluation for suspected ischemic symptoms, a "normal" diagnosis is five times more common than it is in men. These women are often labeled as having cardiac syndrome X, also known as microvascular angina (MVA). MVA is defined as angina pectoris caused by abnormalities of the small coronary arteries, and is characterized by effort chest pain and evidence of myocardial ischemia with a non-invasive stress test, although the coronary arteries can appear normal or near normal by angiography. MVA patients are often neglected due to the assumption of a good prognosis. However, MVA has important prognostic implications and a proper diagnosis is necessary in order to relieve the patients' symptoms and improve clinical outcomes. The coronary microvasculature cannot be directly imaged using coronary angiography, due to the small diameter of the vessels; therefore, the coronary microvascular must be assessed functionally. Treatment of MVA initially includes standard anti-ischemic drugs (β-blockers, calcium antagonists, and nitrates), although control of symptoms is often insufficient. In this review, we discuss the pathophysiology, diagnosis, and treatment of MVA.

Serious cardiac complications in coronary spasm provocation tests using acetylcholine or ergonovine: analysis of 21 512 patients from the diagnosis procedure combination database in Japan

BACKGROUND

Previous studies on complications with coronary spasm provocation tests were based on small sample sizes or were limited to high-volume centers. The risk of provocation tests using acetylcholine (ACH) or ergonovine (ER) remains to be fully examined by a large-scale multicenter study.

HYPOTHESIS

ACH provocation tests are associated with a higher rate of serious cardiac complications than ER tests.

METHODS

Using the Diagnosis Procedure Combination database in Japan, we identified patients aged ≥20 years who underwent a pharmacological provocation test during coronary angiography. We assessed the composite outcome of cardiac complications requiring urgent procedures (defibrillation, chest compression, intra-aortic balloon pumping, or extracorporeal membrane oxygenation) or death on the day of the provocation test, and compared the outcome between ACH and ER tests.

RESULTS

Of 21 512 eligible patients in 602 hospitals, 10 628 (49.4%) underwent an ACH test and 10 884 (50.6%) underwent an ER test. The composite outcome occurred in 141 (0.7%) patients. The ACH group was significantly more likely to have the composite outcome than the ER group (0.9% vs 0.4%, P < 0.001). The propensity-score analyses showed consistent results (propensity score-matched, 0.9% vs 0.4%, P = 0.003; inverse probability-weighted, 0.8% vs 0.4%, P < 0.001). In a multivariable logistic regression analysis, ACH tests were significantly associated with a higher rate of the composite outcome than ER tests (odds ratio: 1.75, 95% confidence interval: 1.13-2.69, P = 0.011).

CONCLUSIONS

This retrospective cohort study suggested that ACH tests were associated with a higher rate of cardiac complications than ER tests.

Clinical implications of provocation tests for coronary artery spasm: safety, arrhythmic complications, and prognostic impact: multicentre registry study of the Japanese Coronary Spasm Association

AIMS

Provocation tests of coronary artery spasm are useful for the diagnosis of vasospastic angina (VSA). However, these tests are thought to have a potential risk of arrhythmic complications, including ventricular tachycardia (VT), ventricular fibrillation (VF), and brady-arrhythmias. We aimed to elucidate the safety and the clinical implications of the spasm provocation tests in the nationwide multicentre registry study by the Japanese Coronary Spasm Association.

METHODS AND RESULTS

A total of 1244 VSA patients (M/F, 938/306; median 66 years) who underwent the spasm provocation tests were enrolled from 47 institutes. The primary endpoint was defined as major adverse cardiac events (MACEs). The provocation tests were performed with either acetylcholine (ACh, 57%) or ergonovine (40%). During the provocation tests, VT/VF and brady-arrhythmias developed at a rate of 3.2 and 2.7%, respectively. Overall incidence of arrhythmic complications was 6.8%, a comparable incidence of those during spontaneous angina attack (7.0%). Multivariable logistic regression analysis demonstrated that diffuse right coronary artery spasm (P < 0.01) and the use of ACh (P < 0.05) had a significant correlation with provocation-related VT/VF. During the median follow-up of 32 months, 69 patients (5.5%) reached the primary endpoint. The multivariable Cox proportional hazard model revealed that mixed (focal plus diffuse) type multivessel spasm had an important association with MACEs (adjusted hazard ratio, 2.84; 95% confidence interval, 1.34-6.03; P < 0.01), whereas provocation-related arrhythmias did not.

CONCLUSION

The spasm provocation tests have an acceptable level of safety and the evaluation of spasm type may provide useful information for the risk prediction of VSA patients.

Current advances in the understanding of coronary vasospasm

Recent years have witnessed progress in our understanding of coronary vasospasm (CVS). It is evident that this is not only an East Asian but also a global disease associated with significant symptoms and possible lethal sequelae for afflicted individuals. A correct diagnosis depends on the understanding of pathogenesis and symptomatology of CVS. With the correct diagnosis, we can manage CVS patients effectively and promptly, providing optimal patient safety. Advances in our understanding of interactions between inflammation, endothelium, and smooth muscle cells have led to substantial progress in understanding the pathogenesis of symptoms in CVS and have provided some insights into the basic etiology of this disorder in some patient subpopulations. We look forward to a time when therapy will address pathophysiology and perhaps, even the primary etiology.

Association of ornithine transcarbamylase gene polymorphisms with hypertension and coronary artery vasomotion

BACKGROUND

Previous studies have suggested that the activity of enzymes involved in the urea cycle may modulate nitric oxide (NO) production, arterial vasomotion, and hypertension. Our aim was to determine whether hypertension and coronary vasomotion could be associated with polymorphisms within the ornithine transcarbamylase (OTC) gene, located on chromosome X and coding for a key-enzyme of the urea cycle.

METHODS

Among 11 OTC polymorphisms that were originally selected from databases, the tag single-nucleotide polymorphism (SNP) rs5963409 and the independent SNP rs1800321 were tested for association with hypertension in two independent population samples recruited in Northern (Multinational MONItoring of trends and determinants in CArdiovascular disease (MONICA) study, n = 1,138) and Western (Etude du Vieillissement Artériel (EVA) study, n = 1,166) France. The vasomotor response of coronary arteries to methylergonovine maleate and isosorbide dinitrate was also evaluated in an independent sample (the vasomotion study, n = 121).

RESULTS

In males, the frequency of the rs5963409 minor allele was consistently higher in hypertensive (HT) than in normotensive subjects in the MONICA and EVA studies. In the combined sample, the rs5963409 minor allele was associated with an increased risk of hypertension (odds ratio (OR) (95% confidence interval (CI)) = 1.45 (1.10-1.90); P = 0.008). This association was independent of classical confounding factors. Consistently, rs5963409 minor allele was associated with a greater susceptibility to vasoconstriction in response to methylergonovine maleate (P = 0.0072). In contrast, no significant association between rs5963409 and hypertension could be detected in females.

CONCLUSION

Our results suggest that the OTC rs5963409 polymorphism may be associated with hypertension and coronary vasomotion in males.

The role of 5-HT on the cardiovascular and renal systems and the clinical potential of 5-HT modulation

The main peripheral sources of 5-hydroxytryptamine (5-HT) are as a neurotransmitter and local hormone in the gastrointestinal tract, and stored in circulating platelets and pulmonary neuroepithelial bodies. 5-HT has been shown to have many possible physiological and pathophysiological roles on the cardiovascular and renal systems. Thus, 5-HT may contribute to valvular heart disease, coronary artery disease, pulmonary hypertension, pulmonary embolism, pre-eclampsia, peripheral vascular disease and diabetic nephropathy. Consequently, modulators of the 5-HT system have diverse clinical potential. For instance, selective 5-HT subtype 3 receptor (5-HT(3)) antagonists may have potential in the treatment of the pain associated with myocardial infarction. MCI-9042 (sarpogrelate) or other 5-HT(2A) antagonists may have clinical potential for the treatment of vasospastic angina, ischaemic heart disease, reperfusion injury and hindlimb ischaemia. Several modulators of 5-HT (5-HT transporter inhibitors, 5-HT(1B) and (2B) antagonists) may have potential alone or in combination in the treatment of pulmonary hypertension. In hypertension, agonists at the 5-HT(7) and antagonists at the 5-HT(2B) may reduce blood pressure, and in diabetes, sarpogrelate may protect against nephropathy.

Multiplicity of mechanisms of serotonin receptor signal transduction

The serotonin (5-hydroxytryptamine, 5-HT) receptors have been divided into 7 subfamilies by convention, 6 of which include 13 different genes for G-protein-coupled receptors. Those subfamilies have been characterized by overlapping pharmacological properties, amino acid sequences, gene organization, and second messenger coupling pathways. Post-genomic modifications, such as alternative mRNA splicing or mRNA editing, creates at least 20 more G-protein-coupled 5-HT receptors, such that there are at least 30 distinct 5-HT receptors that signal through G-proteins. This review will focus on what is known about the signaling linkages of the G-protein-linked 5-HT receptors, and will highlight some fascinating new insights into 5-HT receptor signaling.