Cardiovascular and hormonal effects of calcitonin gene-related peptide in congestive heart failure

Ischemic cardiac stromal fibroblast-derived protein mediators in the infarcted myocardium and transcriptomic profiling at single cell resolution

This article focuses on screening the major secreted proteins by the ischemia-challenged cardiac stromal fibroblasts (CF), the assessment of their expression status and functional role in the post-ischemic left ventricle (LV) and in the ischemia-challenged CF culture and to phenotype CF at single cell resolution based on the positivity of the identified mediators. The expression level of CRSP2, HSP27, IL-8, Cofilin-1, and HSP90 in the LV tissues following coronary artery bypass graft (CABG) and myocardial infarction (MI) and CF cells followed the screening profile derived from the MS/MS findings. The histology data unveiled ECM disorganization, inflammation and fibrosis reflecting the ischemic pathology. CRSP2, HSP27, and HSP90 were significantly upregulated in the LV-CABG tissues with a concomitant reduction ion LV-MI whereas Cofilin-1, IL8, Nrf2, and Troponin I were downregulated in LV-CABG and increased in LV-MI. Similar trends were exhibited by ischemic CF. Single cell transcriptomics revealed multiple sub-phenotypes of CF based on their respective upregulation of CRSP2, HSP27, IL-8, Cofilin-1, HSP90, Troponin I and Nrf2 unveiling pathological and pro-healing phenotypes. Further investigations regarding the underlying signaling mechanisms and validation of sub-populations would offer novel translational avenues for the management of cardiac diseases.

The Role of Calcitonin Gene Related Peptide (CGRP) in Neurogenic Vasodilation and Its Cardioprotective Effects

Calcitonin gene-related peptide (CGRP) is a highly potent vasoactive peptide released from sensory nerves, which is now proposed to have protective effects in several cardiovascular diseases. The major α-form is produced from alternate splicing and processing of the calcitonin gene. The CGRP receptor is a complex composed of calcitonin like receptor (CLR) and a single transmembrane protein, RAMP1. CGRP is a potent vasodilator and proposed to have protective effects in several cardiovascular diseases. CGRP has a proven role in migraine and selective antagonists and antibodies are now reaching the clinic for treatment of migraine. These clinical trials with antagonists and antibodies indicate that CGRP does not play an obvious role in the physiological control of human blood pressure. This review discusses the vasodilator and hypotensive effects of CGRP and the role of CGRP in mediating cardioprotective effects in various cardiovascular models and disorders. In models of hypertension, CGRP protects against the onset and progression of hypertensive states by potentially counteracting against the pro-hypertensive systems such as the renin-angiotensin-aldosterone system (RAAS) and the sympathetic system. With regards to its cardioprotective effects in conditions such as heart failure and ischaemia, CGRP-containing nerves innervate throughout cardiac tissue and the vasculature, where evidence shows this peptide alleviates various aspects of their pathophysiology, including cardiac hypertrophy, reperfusion injury, cardiac inflammation, and apoptosis. Hence, CGRP has been suggested as a cardioprotective, endogenous mediator released under stress to help preserve cardiovascular function. With the recent developments of various CGRP-targeted pharmacotherapies, in the form of CGRP antibodies/antagonists as well as a CGRP analog, this review provides a summary and a discussion of the most recent basic science and clinical findings, initiating a discussion on the future of CGRP as a novel target in various cardiovascular diseases.

Roles of sensory nerves in the regulation of radiation-induced structural and functional changes in the heart

PURPOSE

Radiation-induced heart disease (RIHD) is a chronic severe side effect of radiation therapy of intrathoracic and chest wall tumors. The heart contains a dense network of sensory neurons that not only are involved in monitoring of cardiac events such as ischemia and reperfusion but also play a role in cardiac tissue homeostasis, preconditioning, and repair. The purpose of this study was to examine the role of sensory nerves in RIHD.

METHODS AND MATERIALS

Male Sprague-Dawley rats were administered capsaicin to permanently ablate sensory nerves, 2 weeks before local image-guided heart x-ray irradiation with a single dose of 21 Gy. During the 6 months of follow-up, heart function was assessed with high-resolution echocardiography. At 6 months after irradiation, cardiac structural and molecular changes were examined with histology, immunohistochemistry, and Western blot analysis.

RESULTS

Capsaicin pretreatment blunted the effects of radiation on myocardial fibrosis and mast cell infiltration and activity. By contrast, capsaicin pretreatment caused a small but significant reduction in cardiac output 6 months after irradiation. Capsaicin did not alter the effects of radiation on cardiac macrophage number or indicators of autophagy and apoptosis.

CONCLUSIONS

These results suggest that sensory nerves, although they play a predominantly protective role in radiation-induced cardiac function changes, may eventually enhance radiation-induced myocardial fibrosis and mast cell activity.

Preformed angiotensin II is present in human mast cells

PURPOSE

The density of mast cells increases in the myocardium of patients suffering from heart failure. However, their function remains unclear. In this study, preformed angiotensin II (ANG II), a potent growth factor, was found to be contained in, and released by, human mast cells.

METHODS

The human mast cell line (HMC-1) was incubated with 0 to 10(-6) M calcitonin gene-related peptide (CGRP) or culture medium. The expression of renin-angiotensin system mRNA was examined using RT-PCR analysis. ELISA and immunohistochemistry with monoclonal antibody against human ANG II were performed to detect the presence of ANG II in HMC-1. The effect of CGRP on the expression of angiotensinogen mRNA was examined by quantitative RT-PCR analysis.

RESULTS

Preformed ANG II was detected in a human mast cell line (HMC-1) which is a neoplastic cell line of mast cells by ELISA and immunohistochemistry. Presence of mRNA of angiotensinogen and renin was confirmed by polymerase chain reaction in HMC-1, while mRNA of angiotensin converting enzyme (ACE) was undetectable. Since myocardial mast cells are interfaced with nerve fibers and functionally associated with CGRP, the effect of CGRP on ANG II release from HMC-1 was examined. CGRP induced the release of ANG II and increased angiotensinogen mRNA in HMC-1.

CONCLUSIONS

The presence of preformed ANG II and gene expression of the renin-angiotensin system were detected in human mast cells. The release and synthesis of ANG II in mast cells was regulated by CGRP.

Specific N-terminal CGRP fragments mitigate chronic hypoxic pulmonary hypertension in rats

Chronic hypoxic pulmonary hypertension (HPH) is characterized by elevated pulmonary arterial pressure (P(PA)), right ventricular hypertrophy (RVH), pulmonary vascular remodeling, pulmonary edema and polycythemia. Currently, there is no safe and effective treatment for HPH. Calcitonin gene-related peptide (CGRP) is the most potent peptide vasodilator discovered thus far. We previously demonstrated that exogenous CGRP reversed HPH in rats. However, the CGRP1 receptor antagonist CGRP(8-37) and smaller inhibitory C-terminal CGRP fragments that can be formed by enzymatic cleavage in vivo may compromise the beneficial effects of endogenous or exogenous CGRP. We here examine the agonistic efficacy of N-terminal rat alpha-CGRP peptides containing the disulfide bridge (Cys(2)-Cys(7)) with amidated C-terminal in prevention of HPH. Chronic infusion of CGRP(1-8), CGRP(1-13), or CGRP(1-14) at 7 nmol/h/rat via the right jugular vein during 14 days of hypobaric hypoxia (10% inspired O(2)) significantly decreased the P(PA), RVH and pulmonary arterial medial thickness in comparison with controls, suggesting that these CGRP sequences can mitigate chronic HPH in rats. Systemic pressure was unchanged by infused peptides indicating no carry-over effect. In conclusion, N-terminal CGRP fragments (CGRP(1-8), CGRP(1-13) and CGRP(1-14)) may have a protective role in hypoxic pulmonary hypertension.

Calcitonin gene-related peptide is not essential for the development of pressure overload-induced hypertrophy in vivo

The regulatory neuropeptide calcitonin-gene related peptide (CGRP) has been shown to evoke a hypertrophic response in isolated cardiomyocytes in vitro, an effect which was attributed to PKC activation. Activation of PKC has previously been implicated in the development of cardiac hypertrophy. We therefore investigated the role of CGRP in pressure overload-induced hypertrophy in vivo, which has not previously been reported. Constriction of the ascending aorta of rats resulted in an increase in the heart weight to body weight ratio, increased myocyte diameter, re-expression of the fetal genes ANF, MHCbeta and skeletal alpha-actin, and decreased expression of the adult genes GLUT4 and SERCA2a. Treatment of neonatal rat pups (1-2 days old) with capsaicin (50 mg/kg), resulted in the permanent de-afferentation of small-diameter unmyelinated CGRP-containing sensory C-fibres. Such treatment caused a 68% decrease in the CGRP-like immunoreactivity of hearts isolated from 10 week old rats (p < 0.001). Contrary to expectations, aortic constriction of capsaicin treated rats had no effect on the development of hypertrophy at the trophic, morphometric or gene expression levels. The results suggest that the development of pressure overload-induced hypertrophy in vivo does not require the regulatory neuropeptide CGRP.

Dilatory responses to acetylcholine, calcitonin gene-related peptide and substance P in the congestive heart failure rat

It was examined to what extent congestive heart failure (CHF) in rats, induced by ligation of the left coronary artery, affects the vascular responses to the vasodilatory substances acetylcholine (ACh), calcitonin gene-related peptide (CGRP), and substance P (SP). After induction of CHF status, the basilar, mesenteric and renal arteries and the iliac vein were studied in vitro. Dilatory responses were determined in relation to pre-contraction by the thromboxane mimetic U46619. Sham-operated animals (Sham) served as controls. U46619 induced stronger contraction in CHF basilar and renal arteries compared with the corresponding segments in Sham. ACh induced concentration-dependent dilations in all vessels examined with no difference of maximum relaxation or potency between CHF and Sham. SP induced weak dilations in all arteries examined while the response was markedly attenuated in CHF iliac veins compared with Sham (Emax% 12.2 +/- 3.4 vs. 32.3 +/- 4.8, P = 0.01). The CGRP induced dilation in the CHF basilar artery was weaker (Emax% 18.6 +/- 6.5 vs. 66.9 +/- 5.0, P < 0.001) and less potent (pEC50: 8.2 +/- 0.2 vs. 9.0 +/- 0.2, P = 0.01) compared with Sham. Further, CGRP was less potent in the renal artery of CHF rats compared with Sham (pEC50: 8.1 +/- 0.2 vs. 9.5 +/- 0.3, P < 0.01). In the CHF iliac vein, CGRP was more potent compared with Sham (pEC50: 9.7 +/- 0.4 vs. 8.3 +/- 0.4, P < 0.05). It can be concluded CHF is accompanied by alterations in the vascular response to the dilatory substances studied. The changes differ between vascular beds and between the different substances.

Ionic effects of capsinolol, a calcitonin gene-related peptide releasing beta-adrenoceptor blocker, on isolated cardiac muscles

1. Capsinolol (1.0-30.0 microM) in a cumulating manner decreased the maximum upstroke velocity (Vmax), the action potential amplitude and twitch tension in isolated guinea-pig atria and papillary muscle, rabbit papillary muscle, dog Purkinje fibers and human ventricle tissues. 2. In the isolated guinea-pig atrium, perfusing with capsinolol at 3 microM for 3 min temporarily increased the twitch force and decreased spontaneous cycle length; however, the results were reversed after longer exposure of the tissue. 3. Capsinolol prolonged the duration of action potential in the guinea-pig atrium and rabbit papillary muscles. The maximum diastolic potential was shifted to a less-negative level in dog Purkinje fibers and human ventricular muscles.

Isolated myocyte contractile function is normal in postinfarct remodeled rat heart with systolic dysfunction

BACKGROUND

Postinfarction ventricular remodeling is associated with lengthening and contractile dysfunction of the remote noninfarcted myocardium. Mechanisms underlying this phenomenon remain unclear.

METHODS AND RESULTS

We studied serial changes in global left ventricular (LV) structure and function in infarcted (1, 2, 4, and 6 weeks after myocardial infarction) and sham-operated rat hearts and correlated them with structural and functional changes in myocytes isolated from the remote LV myocardium in the same hearts. Rats with myocardial infarction developed significant remodeling. The heart weight-to-body weight ratios were increased. LV volumes at filling pressure of 10 mm Hg were higher (305+/-28 versus 215+/-12 microL, P<.01). This was accompanied by global LV dysfunction (in vivo LV end-diastolic pressure, 4+/-1 versus 23+/-1.6 mm Hg; Langendorff LV developed pressure, 105+/-4 versus 62+/-9 mm Hg, P<.001 for both). Myocytes isolated from these hearts showed significant structural remodeling (LV myocytes, 24% longer and 15% wider; right ventricular myocytes, 38% longer and 31% wider, all P<.05). LV myocyte length correlated with changes in LV volume (r=.79) and function (LV developed pressure, r=-.81). However, LV myocytes from the same hearts showed normal contractile function and intracellular Ca2+ transients at baseline and during inotropic stimulation with increasing extracellular Ca2+ (1 to 6 mmol/L). The shortening-frequency relationship was also similar in myocytes from sham and myocardial infarction rats.

CONCLUSIONS

Postinfarct LV remodeling occurs predominantly by myocyte lengthening rather than by myocyte slippage. However, contractile function of the unloaded myocytes from the remote noninfarcted LV myocardium of the remodeled heart is normal. Therefore, myocyte contractile abnormalities may not contribute to global dysfunction of the remodeled heart. Reduced myocyte mass and nonmyocyte factors like increased wall stress, altered LV geometry, and changes in the myocardial interstitium may be more important in the genesis of postinfarct LV dysfunction in this model.

Calcitonin gene-related peptide inhibits human platelet aggregation

Calcitonin gene-related peptide (CGRP) is a potent vasodilator in humans. CGRP receptors have also been found in various tissues other than blood vessels, such as the central nervous system, kidney, and heart. However, little is known about the effects of CGRP on human platelets. We investigated the effect of CGRP (human alpha type) on platelet aggregation in 21 healthy subjects (9 men and 12 women, mean age 54.6 years). CGRP inhibited platelet aggregation in vitro in 19 of the subjects (90.5%) in a dose-dependent manner with 50% inhibitory doses of 1.6 mumol/L and 1.1 mumol/L for aggregation induced by epinephrine and collagen, respectively. 125I-labeled CGRP bound specifically to intact platelets. The dissociation constant (Kd) was 61.9 +/- 17.7 pmol and the maximum number of binding sites (Bmax) was 5.4 +/- 3.9 pmol/10(9) platelets. The CGRP analogue (8-37)CGRP, but not calcitonin, inhibited the binding of 125I-CGRP to platelets. CGRP (5 mumol/L), but not (8-37)CGRP or calcitonin, increased the platelet cyclic AMP (cAMP) concentration by 31.7 +/- 3.6%. Thus, CGRP inhibits platelet aggregation via a specific receptor and by increasing the platelet cAMP concentration. CGRP may play a role in the modulation of platelet function in humans.

Histamine H3-receptor-mediated inhibition of calcitonin gene-related peptide release from cardiac C fibers. A regulatory negative-feedback loop

Antidromic stimulation of cardiac sensory C fibers releases calcitonin gene-related peptide (CGRP), which increases heart rate, contractility, and coronary flow. C-fiber endings are closely associated with mast cells, and CGRP may release mast-cell histamine. Because prejunctional histamine H3-receptors inhibit transmitter release from autonomic nerves, we tested the hypothesis that H3-receptors modulate CGRP release in the heart. CGRP released by bradykinin in the electrically paced guinea pig left atrium and by capsaicin in the spontaneously beating isolated heart caused marked positive inotropic and chronotropic effects, respectively. Capsaicin significantly enhanced the overflow of CGRP (fivefold) and histamine (twofold) into the coronary effluent. All of these effects were prevented by prior chemical destruction of C fibers in vivo. The H3-receptor agonist imetit attenuated the inotropic response to bradykinin by 50%. Imetit also decreased the capsaicin-induced tachycardia and the increase in CGRP overflow by 50%. Imetit, however, did not modify the response to exogenous CGRP. The effects of imetit were blocked by the H3-receptor antagonist thioperamide. Notably, thioperamide by itself potentiated the capsaicin-evoked increases in heart rate and CGRP overflow (by 25% and 50%, respectively). Thus, our findings identify a negative-feedback loop, whereby CGRP releases histamine from cardiac mast cells and histamine in turn inhibits CGRP releases by activating H3-receptors on C-fiber terminals. Because CGRP release is augmented in pathophysiological conditions, such as septic shock, heart failure, and acute myocardial infarction, modulation of CGRP release may be clinically relevant.

Cardiovascular and hormonal responses to a meal in hypertrophic cardiomyopathy: a comparison of patients with and without postprandial exacerbation of symptoms

Some patients with hypertrophic cardiomyopathy experience postprandial exacerbation of symptoms. The aim of this study was to determine whether the hemodynamic and/or hormonal responses to a meal differ between patients with and without postprandial symptoms. Ten hypertrophic cardiomyopathy patients with postprandial symptoms, 10 patients without postprandial symptoms, and 10 normal subjects ate a 740 Kcal meal, following which heart rate, blood pressure, and echocardiographic and gastrointestinal hormone changes were compared among the three groups. Heart rate increased (p < 0.001) and diastolic blood pressure fell (p < 0.001) to a similar degree in the three groups. Left ventricular outflow tract velocity increased (p < 0.01) and some patients had substantial increases in outflow tract pressure gradient; however, this was independent of the presence or absence of postprandial symptoms. The atrial contribution to filling increased in normal subjects and in both groups of hypertrophic cardiomyopathy patients. There was no significant difference in the gastrointestinal hormone changes in the three groups. In summary, there is no evidence for a distinctive hemodynamic or hormonal response to food in hypertrophic cardiomyopathy patients with postprandial symptoms. These symptoms more likely reflect differences in underlying cardiac disease characteristics and severity.

Calcitonin gene-related peptide is not elevated in rat plasma by heart failure or by neutral endopeptidase inhibition

Some studies have indicated that plasma calcitonin gene-related peptide (CGRP) increases in congestive heart failure (CHF). In vitro, neutral endopeptidase (NEP) cleaves CGRP. We studied CGRP-like immunoreactivity (CGRP-ir) in rat plasma in a coronary artery-ligation model of CHF with and without NEP inhibition. Rats with CHF (n = 6) and sham-operated controls (n = 6) were administered vehicle and, separately, SCH 34826, a NEP inhibitor, subcutaneously 90 mg/kg. Plasma sample was taken 60 minutes later. Seventeen untreated coronary-ligated rats with various degrees of CHF were studied separately. Systolic arterial pressure (SAP) was measured while conscious. All rats were killed by exsanguination, and heart and lungs were removed and weighed. In CHF rats, plasma atrial natriuretic peptide after vehicle (basal ANP) was 7.6-fold, but basal CGRP-ir was similar compared to controls. After SCH 34826, plasma CGRP-ir decreased marginally in CHF rats (57-> 51 ng/l, p = 0.011), and ANP increased 1.8-fold (418-> 730 ng/l, p = 0.001). In controls, these changes by SCH 34826 were small. Basal ANP correlated strongly with relative weight of heart (HE; R = 0.93, p < 0.001) and lungs (LU; R = 0.96, p < 0.001). There was no correlation between basal CGRP-ir, basal plasma renin activity (PRA), HE and LU. In the untreated coronary-ligated rats, plasma CGRP-ir did not correlate with HE, LU, SAP, plasma ANP or PRA, but plasma ANP correlated with HE (R = 0.62, p = 0.011) and LU (R = 0.70, p = 0.002). We conclude that, in rat plasma, CGRP-ir is not elevated either by NEP inhibition, or in post-infarction CHF.

Calcitonin gene-related peptide in treatment of severe peripheral vascular insufficiency in Raynaud's phenomenon

Calcitonin gene-related peptide (CGRP) is a potent vasodilator that may be involved in the regulation of the peripheral circulation and in its response to cold. There is evidence that CGRP in digital cutaneous perivascular nerves is deficient in Raynaud's phenomenon. Our pilot study of intravenous CGRP suggested that this substance is beneficial in patients with Raynaud's phenomenon; here we have extended our studies. Ten patients with severe Raynaud's phenomenon secondary to connective tissue disease were randomly assigned to groups receiving intravenous CGRP (0.6 micrograms/min for 3 h per day on 5 days) or saline. Hand and digital blood flow and skin temperature were measured by thermocouple and laser doppler flowmetry. Blood flow was significantly (p < 0.05) increased by CGRP in both hands (median blood flow after infusion as percentage of baseline reading 179 [range 100-355]%) and fingers (149 [100-161]%); saline had no effect (hands 102 [84-123]%, fingers 96 [81-113]%). Hand temperature was increased more by CGRP than by saline (2.8 [1.5-4.0] vs 1.0 [-1.0 to 2.5] degrees C, p < 0.05). Digital temperature increased after CGRP but the difference between the treatment groups in temperature rise was not significant, perhaps because saline caused increases in some patients. All ulcers healed in four of five CGRP-treated patients but in no saline-treated patients. Thus intravenous CGRP effectively dilates the compromised digital cutaneous vasculature in severe Raynaud's phenomenon.

Calcitonin gene-related peptide: a haemodynamic study of a novel vasodilator in patients with severe chronic heart failure

The haemodynamic and neurohumeral response to a novel vasodilator calcitonin gene-related peptide was assessed in 11 patients with severe chronic heart failure. To assess tolerance, a continuous 48-h infusion (n = 6) was compared with a regimen of two successive 8-h infusions (n = 5). Haemodynamic response profiles were similar for both regimens, though the continuous infusion was poorly tolerated. Reductions in afterload reflected by changes in systemic vascular resistance and systemic blood pressure led to increases in cardiac index of at least 24%. Increments in heart rate accounted for much of the increase in cardiac output, there being no significant change in stroke volume index. The response was maintained over the 48-h study period with no tachyphylaxis. Renin and angiotensin levels increased significantly after 24 h. Calcitonin gene-related peptide exerts a favourable haemodynamic response in patients with severe heart failure. The dose used in this study, however, caused troublesome side-effects, particularly when given by continuous infusion. Further studies are required to establish the therapeutic range of this new peptide.

Effects of calcitonin gene-related peptide on cardiac contractility, coronary hemodynamics and myocardial energetics in idiopathic dilated cardiomyopathy

This study was performed to examine the effects of calcitonin gene-related peptide on cardiac function and coronary circulation in patients with heart failure. Synthetic human calcitonin gene-related peptide was infused in the left main coronary artery of 9 patients undergoing cardiac catheterization at different doses corresponding to incremental infusion rates of 15, 50, 150 and 600 pmol.min-1. No hemodynamic change was observed in response to administration of the 2 lowest doses. The 2 highest doses induced an increase in cardiac index and a decrease in systemic arterial pressure. The infusion of 600 pmol.min-1 resulted in a decrease of mean systemic arterial pressure (86.8 +/- 6.5 to 71.8 +/- 4.9 mm Hg; p less than 0.01), and an increase in both cardiac index (2.1 +/- 0.1 to 3.1 +/- 0.17 liters.min-1.m-2; p less than 0.01) and heart rate (87 +/- 3.7 to 101 +/- 6.1 beats.min-1; p less than 0.01). These hemodynamic changes were associated with a significant increase in plasma norepinephrine and epinephrine concentrations. Peak positive first derivative of left ventricular pressure did not change at any infusion rate. Left ventricular end-diastolic pressure decreased at the 2 highest doses associated with a decrease in plasma atrial natriuretic factor concentration (730 +/- 140 to 436 +/- 115 pg.ml-1; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitonin gene-related peptide is a venous dilator in conscious rats

The effect of calcitonin gene-related peptide (CGRP) on body venous tone is not known. This study examines the dose-response effects of rat alpha CGRP on mean circulatory filling pressure (MCFP), an index of body venous tone, in conscious rats. Dose-response curves of CGRP were constructed in three groups of rats, namely, (I) intact, (III) rats pretreated with the ganglionic blocker hexamethonium and (V) rats pretreated with noradrenaline to raise mean arterial pressure (MAP) and MCFP. Three additional groups, (II), (IV) and (VI), served as time controls and were treated similarly to (I), (III) and (V), respectively, except that they were given saline (0.9% NaCl) in place of CGRP. The infusion of CGRP in intact rats dose dependently decreased MAP, increased heart rate (HR) and slightly reduced MCFP. In ganglionic-blocked rats, CGRP caused similar depressor responses but less tachycardia than in intact rats, however, it also slightly reduced MCFP. In rats given noradrenaline, CGRP dose dependently decreased MAP, MCFP and increased HR. The results show that CGRP has venodilator activities; its venous effect is best revealed at elevated venous tone.

Effects of prolonged infusion of human alpha calcitonin gene-related peptide on hemodynamics, renal blood flow and hormone levels in congestive heart failure

We have previously demonstrated that short-term infusion of calcitonin gene-related peptide (CGRP) has beneficial effects in congestive heart failure. The effects of prolonged infusion of CGRP on hemodynamic functions, plasma hormones and renal blood flow were studied in 9 patients with congestive heart failure (New York Heart Association class III or IV, ejection fraction less than 35%). Hemodynamic variables were measured at 30-minute intervals for 8 hours during CGRP infusion (8 ng/kg/min) and for 2 hours after discontinuation. CGRP caused a decrease in right atrial (28%, p less than 0.05), pulmonary artery (22%, p less than 0.02), pulmonary artery wedge (37%, p less than 0.001) and systemic arterial (18%, p less than 0.05) pressures. Systemic vascular resistance decreased more than pulmonary vascular resistance. Cardiac output (72%, p less than 0.001) and stroke volume (60%, p less than 0.02) increased. Heart rate did not change. There was no evidence of tolerance throughout the infusion. The hemodynamic effects were lost within 30 minutes of stopping CGRP. Renal blood flow (34%, p less than 0.01) and glomerular filtration rate (43%, p less than 0.01) increased. Atrial natriuretic peptide decreased (p less than 0.05), while plasma cortisol (p less than 0.02) increased. Plasma epinephrine, norepinephrine, renin activity, aldosterone and growth hormone were unchanged. It is concluded that in patients with severe congestive heart failure, CGRP has sustained beneficial effects on hemodynamic functions and has no adverse effects on hormones. Unlike many other vasodilators, CGRP also increases renal blood flow and glomerular filtration.