Nutrition and Lifestyle-Related Factors as Predictors of Muscle Atrophy in Hematological Cancer Patients.

BACKGROUND: Cancer and side effects from cytostatic treatment commonly affect nutritional status manifested as a decrease in muscle mass. We aimed to investigate the impact of nutrition and lifestyle-related factors on muscle mass in patients with hematological cancer. METHODS: Dietary intake, food preferences, quality of life (QoL), and physical activity level (PAL) were monitored during 1-2 cytostatic treatment series. Body composition was estimated using bioelectrical impedance analysis (BIA). RESULTS: 61 patients were included. Weight loss and loss of muscle mass were detected in 64% and 59% of the patients, respectively. Muscle mass was significantly positively correlated to increasing PAL (p = 0.003), while negatively correlated to increasing age (p = 0.03), physical QoL (p = 0.007), functional QoL (p = 0.05), self-perceived health (p = 0.004), and self-perceived QoL (p = 0.007). Weight was significantly positively correlated to increased intake of soft drinks (p = 0.02) as well as the favoring of bitter grain and cereal products (p = 0.03), while negatively correlated to increasing age (p = 0.03) and increasing meat intake (p = 0.009) Conclusions: Several nutritional and lifestyle-related factors affected change in body composition. The clinical significance of these changes should be investigated in controlled, interventional studies.

First-Line Venetoclax Combinations in Chronic Lymphocytic Leukemia.

BACKGROUND: Randomized trials of venetoclax plus anti-CD20 antibodies as first-line treatment in fit patients (i.e., those with a low burden of coexisting conditions) with advanced chronic lymphocytic leukemia (CLL) have been lacking. METHODS: In a phase 3, open-label trial, we randomly assigned, in a 1:1:1:1 ratio, fit patients with CLL who did not have TP53 aberrations to receive six cycles of chemoimmunotherapy (fludarabine-cyclophosphamide-rituximab or bendamustine-rituximab) or 12 cycles of venetoclax-rituximab, venetoclax-obinutuzumab, or venetoclax-obinutuzumab-ibrutinib. Ibrutinib was discontinued after two consecutive measurements of undetectable minimal residual disease or could be extended. The primary end points were undetectable minimal residual disease (sensitivity, <10-4 [i.e., <1 CLL cell in 10,000 leukocytes]) as assessed by flow cytometry in peripheral blood at month 15 and progression-free survival. RESULTS: A total of 926 patients were assigned to one of the four treatment regimens (229 to chemoimmunotherapy, 237 to venetoclax-rituximab, 229 to venetoclax-obinutuzumab, and 231 to venetoclax-obinutuzumab-ibrutinib). At month 15, the percentage of patients with undetectable minimal residual disease was significantly higher in the venetoclax-obinutuzumab group (86.5%; 97.5% confidence interval [CI], 80.6 to 91.1) and the venetoclax-obinutuzumab-ibrutinib group (92.2%; 97.5% CI, 87.3 to 95.7) than in the chemoimmunotherapy group (52.0%; 97.5% CI, 44.4 to 59.5; P<0.001 for both comparisons), but it was not significantly higher in the venetoclax-rituximab group (57.0%; 97.5% CI, 49.5 to 64.2; P = 0.32). Three-year progression-free survival was 90.5% in the venetoclax-obinutuzumab-ibrutinib group and 75.5% in the chemoimmunotherapy group (hazard ratio for disease progression or death, 0.32; 97.5% CI, 0.19 to 0.54; P<0.001). Progression-free survival at 3 years was also higher with venetoclax-obinutuzumab (87.7%; hazard ratio for disease progression or death, 0.42; 97.5% CI, 0.26 to 0.68; P<0.001), but not with venetoclax-rituximab (80.8%; hazard ratio, 0.79; 97.5% CI, 0.53 to 1.18; P = 0.18). Grade 3 and grade 4 infections were more common with chemoimmunotherapy (18.5%) and venetoclax-obinutuzumab-ibrutinib (21.2%) than with venetoclax-rituximab (10.5%) or venetoclax-obinutuzumab (13.2%). CONCLUSIONS: Venetoclax-obinutuzumab with or without ibrutinib was superior to chemoimmunotherapy as first-line treatment in fit patients with CLL. (Funded by AbbVie and others; GAIA-CLL13 ClinicalTrials.gov number, NCT02950051; EudraCT number, 2015-004936-36.).

Risk of diabetes and the impact on preexisting diabetes in patients with lymphoma treated with steroid-containing immunochemotherapy.

First-line treatments for lymphomas often include high doses of prednisolone, but the risks of new-onset diabetes mellitus (DM) or worsening of preexisting DM following treatment with cyclic high dose corticosteroids is unknown. This cohort study matched non-Hodgkin lymphoma (NHL) patients treated with steroid-containing immunochemotherapy (ie, R-CHOP[-like] and R-CVP) between 2002 and 2015 to individuals from the Danish population to investigate the risks of new-onset DM. For patients with preexisting DM, the risks of insulin dependency and anthracycline-associated cardiovascular diseases (CVDs) were assessed. In total, 5672 NHL patients and 28 360 matched comparators were included. Time-varying incidence rate ratios (IRRs) showed increased risk of DM in the first year after treatment compared with matched comparators, with the highest IRR being 2.7. The absolute risks were higher among patients in the first 2 years, but the difference was clinically insignificant. NHL patients with preexisting DM had increased risks of insulin prescriptions with 0.5-, 5-, and 10-year cumulative risk differences of insulin treatment of 15.3, 11.8, and 6.0 percentage units as compared with the DM comparators. In a landmark analysis at 1 year, DM patients with lymphoma had decreased risks of insulin dependency compared with comparators. Time-varying IRRs showed a higher CVD risk for NHL patients with DM as compared with comparators in the first year after treatment. NHL patients treated with steroid-containing immunochemotherapy regimens have a clinically insignificant increased risk of DM in the first year following treatment, and patients with preexisting DM have a temporary increased risk of insulin prescriptions and CVD.

Minimal residual disease-guided stop and start of venetoclax plus ibrutinib for patients with relapsed or refractory chronic lymphocytic leukaemia (HOVON141/VISION): primary analysis of an open-label, randomised, phase 2 trial.

BACKGROUND: Targeted time-limited treatment options are needed for patients with relapsed or refractory chronic lymphocytic leukaemia. The aim of this study was to investigate the efficacy of minimal residual disease (MRD)-guided, time-limited ibrutinib plus venetoclax treatment in this patient group. METHODS: HOVON141/VISION was an open-label, randomised, phase 2 trial conducted in 47 hospitals in Belgium, Denmark, Finland, the Netherlands, Norway, and Sweden. Eligible participants were aged 18 years or older with previously treated chronic lymphocytic leukaemia with or without TP53 aberrations; had not been exposed to Bruton tyrosine-kinase inhibitors or BCL2 inhibitors; had a creatinine clearance rate of 30 mL/min or more; and required treatment according to International Workshop on Chronic Lymphocytic Leukemia 2018 criteria. Participants with undetectable MRD (<10-4; less than one chronic lymphocytic leukaemia cell per 10 000 leukocytes) in peripheral blood and bone marrow after 15 28-day cycles of oral ibrutinib (420 mg once daily) plus oral venetoclax (weekly ramp-up 20 mg, 50 mg, 100 mg, 200 mg, up to 400 mg once daily) were randomly assigned (1:2) to ibrutinib maintenance or treatment cessation. Patients who were MRD positive continued to receive ibrutinib monotherapy. Patients who became MRD (>10-2) during observation reinitiated treatment with ibrutinib plus venetoclax. The primary endpoint was progression-free survival at 12 months after random assignment in the treatment cessation group. Progression-free survival was analysed in the intention-to-treat population. All patients who received at least one dose of study drug were included in the safety assessment. The study is registered at ClinicalTrials.gov, NCT03226301, and is active but not recruiting. FINDINGS: Between July 12, 2017, and Jan 21, 2019, 230 patients were enrolled, 225 of whom were eligible. 188 (84%) of 225 completed treatment with ibrutinib plus venetoclax and were tested for MRD at cycle 15. After cycle 15, 78 (35%) patients had undetectable MRD and 72 (32%) were randomly assigned to a treatment group (24 to ibrutinib maintenance and 48 to treatment cessation). The remaining 153 patients were not randomly assigned and continued with ibrutinib monotherapy. Median follow-up of 208 patients still alive and not lost to follow-up at data cutoff on June 22, 2021, was 34·4 months (IQR 30·6-37·9). Progression-free survival after 12 months in the treatment cessation group was 98% (95% CI 89-100). Infections (in 130 [58%] of 225 patients), neutropenia (in 91 [40%] patients), and gastrointestinal adverse events (in 53 [24%] patients) were the most frequently reported; no new safety signals were detected. Serious adverse events were reported in 46 (40%) of 116 patients who were not randomly assigned and who continued ibrutinib maintenance after cycle 15, eight (33%) of 24 patients in the ibrutinib maintenance group, and four (8%) of 48 patients in the treatment cessation group. One patient who was not randomly assigned had a fatal adverse event (bleeding) deemed possibly related to ibrutinib. INTERPRETATION: These data point to a favourable benefit-risk profile of MRD-guided, time-limited treatment with ibrutinib plus venetoclax for patients with relapsed or refractory chronic lymphocytic leukaemia, suggesting that MRD-guided cessation and reinitiation is feasible in this patient population. FUNDING: AbbVie and Janssen.

SARS-CoV-2 infection among patients with haematological disorders: Severity and one-month outcome in 66 Danish patients in a nationwide cohort study.

OBJECTIVES: Patients with haematological disorders may be particularly vulnerable to respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; however, this is unknown. METHODS: We conducted a prospective, nationwide study including 66 patients in follow-up at Danish haematology departments with a malignant or non-malignant haematological disorder and with verified SARS-CoV-2 infection. Outcomes were intensive care unit (ICU) admission and one-month survival rate. RESULTS: Mean age was 66.7 years, 60.6% were males, 90.9% had comorbidity, and 13.6% had a BMI ≥ 30. The most frequent diagnoses were chronic lymphocytic leukaemia/lymphoma (47.0%), multiple myeloma (16.7%) and acute leukaemia/myelodysplastic syndrome (AL/MDS) (12.1%). Treatment for the haematological disease was ongoing in 59.1% of cases. Neutropenia was present in 6.5%, lymphopenia in 46.6% and hypogammaglobulinaemia in 26.3%. The SARS-CoV-2 infection was mild in 50.0%, severe in 36.4% and critical in 13.6%. After one month, 21.2% had been admitted to ICU, and 24.2% died. Mortality was highest in older patients, patients with severe/critical SARS-CoV-2 infection, high comorbidity score or high performance status score, purine analogue treatment and with AL/MDS. Although older patients and patients with comorbidities had the highest mortality rates, mortality was considerable among all haematological patients. CONCLUSION: Haematological patients with SARS-CoV-2 infection has a severe clinical course.

Prognostic significance of infectious episodes occurring during first-line therapy for diffuse large B-cell lymphoma - A nationwide cohort study.

Infections during first-line therapy for DLBCL are often associated with chemotherapy dose reductions and increased mortality. Systemic infections have also been suggested as beneficial promotors of immunological responses. However, whether there is an association between the timing of an infectious episode and outcome during treatment has not yet been clarified. We investigated how the occurrence and timing of infectious episodes during the first line of treatment for "de novo" DLBCL influenced patient outcome. We used data on DLBCL patients from the Danish Lymphoma Registry, the Danish National Patient Registry, and the Danish National Pathology Registry. Infections were categorized according to type (ICD-10) and time of occurrence after treatment start. "Early" infections were defined as occurring between days 7 and 42 and "late" infections between days 100 and 150 from treatment start. Patients experiencing both "early and late" infections were categorized separately. We used multivariable Cox regression and Kaplan-Meier estimates to assess the association between infections and survival adjusting for NCCN-IPI, sex, comorbidity, and rituximab treatment. We identified 3546 patients, median age 65 years (IQR 56,73). Infectious episodes occurred in 1171 (33%) patients, of which 666 had "early," 303 "late," and 202 both "early and late" events. Patients without registered infections had a 5-year overall survival (OS) rates of 74%. Those with "early," "late," or "early+late" had 5-year OS of 65%, 62%, and 53%, respectively. Compared with patients without any registered infections, hazard rate ratios (HR) were 1.24 (95% CI 1.05-1.47), 1.32 (95% CI 1.06-1.63), and 1.59 (95% CI 1.27-2.00), respectively, in the multivariable model. We observed that infectious episodes during first-line treatment for "de novo" DLBCL occurred in 44% of the patients. Irrespective of timing, patients with infectious episodes had an inferior outcome compared to those without. Outcome patterns were similar for patients registered with sepsis.

Richter's transformation in patients with chronic lymphocytic leukaemia: a Nationwide Epidemiological Study.

Richter's transformation (RT) refers to the development of an aggressive lymphoma in patients with chronic lymphocytic leukemia (CLL). Approximately, 2-10% of patients with CLL develop RT, most often as diffuse large B-cell lymphoma. To assess the incidence of RT, we examined risk factors for RT and death among patients with RT in a nationwide CLL cohort (from 2008 to 2016). Among 3772 patients, 113 had biopsy-proven RT. With a median follow-up of 4.3 years, the 5-year cumulative incidence of RT was 2.8%. Advanced Binet stage (B/C) (p<.001), unmutated IGHV (p<.001), and del(17p) (p<.001) were independently associated with risk of developing RT. Half of the patients with RT (49%) were treatment-naïve prior to transformation and demonstrated longer survival after RT compared to patients previously treated for CLL (6.1 vs. 2.8 years, p=.03). Whether this finding could be explained by a higher proportion of clonally unrelated RT among treatment-naïve patients, remain to be addressed.

Risk of death, relapse or progression, and loss of life expectancy at different progression-free survival milestones in primary central nervous system lymphoma.

In this study, we analyzed the evolution of the prognosis of primary central nervous system lymphoma (PCNSL) patients as they reach selected progression-free survival (PFS) milestones after high-dose methotrexate (HD-MTX)-based therapy. In total, 258 and 146 patients were included from Denmark and British Columbia, respectively. All patients were diagnosed during 2000-2017. The 5-year PFS was 27% (95% CI 23; 32); however, for patients reaching 5 years of PFS, this increased to 71% (95% CI 57; 86). Within the first 5 years after diagnosis, patients lost 2.0 years (95% CI 1.8; 2.2) when compared to a similar background population. This reduced to 0.5 years (95% CI 0.2; 0.9) for patients reaching 5 years of PFS. Treatment with rituximab was associated with improved outcomes. The prognosis of patients with PCNSL treated with HD-MTX-based regimens in this cohort is poor, although it improves as patients survive without progression/relapse. However, survival does not conclusively normalize to that of a similar background population.

Depth of neutrophil nadir after first cycle of R-CHOP predicts outcome in diffuse large B-cell lymphoma - a nationwide population-based cohort study.

We investigated if survival was predicted by nadir neutrophil counts after the first cycle of R-CHOP in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL). Neutrophil counts (109/L) were categorized in four grades in the nadir time frame. Prognostic indices and comorbidity levels were calculated and used to adjust the Cox regression model. Kaplan-Meier and Cox regression methods were used to estimate and compare survival. We identified 965 patients. Grade 4 neutropenia was present in 432 (45%). Grade 0 patients had a 5-year overall survival of 67%, grade 1-2: 78%, grade 3: 64%, and grade 4: 57%. Compared with grade 0 adjusted hazard ratios (HR) for death were: 0.77 (95% CI 0.49-1.21) for grade 1-2, 1.18 (95% CI 0.82-1.71) for grade 3, and 1.33 (95% CI 1.02-1.73) for grade 4. Grade 4 neutropenia after the 1st cycle of chemotherapy predicted inferior outcome compared with grade 0 and 1-2. Grade 1-2 neutropenia seemed to have superior outcome.

A case report: metastasis of melanoma to the heart in an era of immunotherapy.

BACKGROUND: Cardiac metastasis of melanoma rarely causes heart failure symptoms and the recognition of cardiac involvement is in most cases first established post-mortem. Surgical removal might be considered in selected cases in patients with an inflow or outflow tract obstruction even though the survival remains poor. Frequently, the metastasis cannot be removed and therapeutic options include conventional chemotherapy or immunotherapy, which is currently recommended as first-line treatment. Since the introduction of immunotherapy survival in metastatic disease has significantly increased but data on patients treated for melanoma with cardiac involvement are scarce. CASE SUMMARY: A 65-year-old man presented with dyspnoea and fatigue. Computed tomography scan revealed tumour processes in the heart, which was confirmed on echocardiography. Biopsies taken from fluorodeoxyglucose positron emission tomography positive lymph nodes in the axilla and groin showed melanoma. Analyses did not reveal BRAF mutation and the PD-L1 expression in tumour cells was below 1%. Treatment with ipilimumab and nivolumab was initiated and cardiopulmonary symptoms subsided during the following months with significant reduction in cardiac metastasis on echocardiography. Unfortunately, the patient developed immune checkpoint inhibitor-induced colitis and could no longer continue on the therapy. Due to development of extra-cardiac and cerebral metastasis, he was referred to palliative care. DISCUSSION: This case demonstrates that timely treatment with immunotherapy could be a safe and effective option for melanoma with cardiac involvement. During treatment, the patient developed severe colitis, a known side effect to immunotherapy. Though this often can be managed with steroids it complicates further treatment.

Cumulative anthracycline exposure and risk of cardiotoxicity; a Danish nationwide cohort study of 2440 lymphoma patients treated with or without anthracyclines.

Cardiotoxicity is a known risk of anthracycline treatment. However, the relative contribution of anthracyclines to the development of congestive heart failure (CHF), when included in a poly-chemotherapy regimen, is unclear. We examined cardiotoxicity in adult patients with diffuse large B-cell lymphoma and follicular lymphoma undergoing first-line immunochemotherapy from 2000-2012. In total, 2440 patients without previous heart disease were identified from the Danish Lymphoma Registry, of which 1994 (81·7%) were treated with anthracycline-containing chemotherapy [R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) or R-CHOEP (R-CHOP + etoposide)] and 446 (18·3%) were treated without anthracyclines (reference group). Compared to the reference group, the adjusted hazard ratio of CHF after 3-5 cycles of R-CHOP/CHOEP was 5·0 [95% confidence interval (CI) 1·4; 18·5], 6 cycles 6·8 (95% CI 2·0; 23·3) and >6 cycles 13·4 (95% CI 4·0; 45·0). The cumulative 5-year risk of CHF with all-cause mortality as competing risk was 4·6% after 3-5 cycles of R-CHOP/CHOEP, 4·5% after 6 and 7·9% after more than 6 cycles. Cumulative 5-year risk for patients treated without anthracyclines was 0·8%. Using anthracyclines in first-line lymphoma treatment increases risk of CHF in patients without previous history of heart disease. In particular, treatment with >6 cycles of R-CHOP/CHOEP is associated with a significant increase in CHF rate.

Trends in prescription of cardiovascular drugs to children in relation to prevalence of CHD from 1999 to 2016.

IntroductionOwing to massive improvements in the diagnostics and surgery of children with CHD, fatality has decreased substantially. As more children with CHD survive from infancy into later childhood, more will need medication for chronic heart failure. However, surprisingly little is actually known about which drugs are being used to treat children with CHD, and whether prescription rates and CHD prevalence have changed over time. OBJECTIVE: The objective of this study was to assess the total prescription of cardiovascular drugs to children during an 18-year period and to assess concomitant CHD prevalence. METHODS: All prescription data of cardiovascular drugs to children aged 0-19 years were extracted from publicly available databases in Norway and Denmark from 1999 to 2016. This was coupled with data on CHD prevalence and birth rates. RESULTS: The number of defined daily doses of cardiovascular drugs prescribed to children doubled in the study period. This was because of an increased use of beta blockers, angiotensin-converting-enzyme inhibitors/angiotensin receptor blockers, and anti-arrhythmic agents. The use of some classes of drugs was significantly reduced over time. The prevalence of CHD remained constant in both countries - 80 per 10,000 births. CONCLUSION: We show that there is an increase in the overall prescription of cardiovascular drugs to children. Beta blockers, angiotensin-converting enzyme/angiotensin receptor blockers, and anti-arrhythmics account for the largest increase. Birth rates decreased or remained constant together with CHD prevalence, suggesting that the increased use of cardiovascular drugs reflected increased prescription per patient, rather than more patients receiving a constant amount of drugs.

Plaque burden influences accurate classification of fibrous cap atheroma by in vivo optical coherence tomography in a porcine model of advanced coronary atherosclerosis.

AIMS: In vivo validation of coronary optical coherence tomography (OCT) against histology and the effects of plaque burden (PB) on plaque classification remain unreported. We aimed to investigate this in a porcine model with human-like coronary atherosclerosis. METHODS AND RESULTS: Five female Yucatan D374Y-PCSK9 transgenic hypercholesterolaemic minipigs were implanted with a coronary shear-modifying stent to induce advanced atherosclerosis. OCT frames (n=201) were obtained 34 weeks after implantation. Coronary arteries were perfusion-fixed, serially sectioned and co-registered with OCT using a validated algorithm. Lesions were adjudicated using the Virmani classification and PB assessed from histology. OCT had a high sensitivity, but modest specificity (92.9% and 74.6%), for identifying fibrous cap atheroma (FCA). The reduced specificity for OCT was due to misclassification of plaques with histologically defined pathological intimal thickening (PIT) as FCA (46.1% of the frames with histological PIT were misclassified). PIT lesions misclassified as FCA by OCT had a statistically higher PB than in other OCT frames (median 32.0% versus 13.4%; p<0.0001). Misclassification of PIT lesions by OCT occurred when PB exceeded approximately 20%. CONCLUSIONS: Compared with histology, in vivo OCT classification of FCA had high sensitivity but reduced specificity due to misclassification of PITs with high PB.

Vascular flow reserve as a link between long-term blood pressure level and physical performance capacity in mammals.

Mean arterial pressure (MAP) is surprisingly similar across different species of mammals, and it is, in general, not known which factors determine the arterial pressure level. Mammals often have a pronounced capacity for sustained physical performance. This capacity depends on the vasculature having a flow reserve that comes into play as tissue metabolism increases. We hypothesize that microvascular properties allowing for a large vascular flow reserve is linked to the level of the arterial pressure.To study the interaction between network properties and network inlet pressure, we developed a generic and parsimonious computational model of a bifurcating microvascular network where diameter and growth of each vessel evolves in response to changes in biomechanical stresses. During a simulation, the network develops well-defined arterial and venous vessel characteristics. A change in endothelial function producing a high precapillary resistance and thus a high vascular flow reserve is associated with an increase in network inlet pressure. Assuming that network properties are independent of body mass, and that inlet pressure of the microvascular network is a proxy for arterial pressure, the study provides a conceptual explanation of why high performing animals tend to have a high MAP.

Support with intra-aortic balloon pump vs. Impella2.5® and blood flow to the heart, brain and kidneys - an experimental porcine model of ischaemic heart failure.

BACKGROUND: Cardiogenic shock as a complication to an acute myocardial infarction has an unacceptably high death rate that has not changed for the last 15years. Mortality is partly related to organ hypoperfusion and mechanical assist devices are used for the most severe cases but we do not know which assist device is the best option. Therefore, we have investigated how an IABP and an Impella®-pump influenced blood flow to the brain, heart and kidneys, in a closed-chest porcine model of severe left ventricular failure. METHODS: 13 pigs were anesthetised and left ventricular failure was induced by occluding the proximal LAD for 45min followed by 30min of reperfusion. Blood flow was measured in the carotid artery, the LAD, and the renal artery. The Impella® and IABP were inserted via the femoral arteries, and the two devices were tested individually and combined after induction of heart failure. RESULTS: Carotid- (p=0.01) and renal blood flow (p=0.045) were higher on Impella®-support, compared to no support. None of the devices altered the blood flow in the LAD. Cardiac power output (p<0.005) and left ventricular work (p<0.00) were also higher on Impella®-support compared to no support. CONCLUSION: Haemodynamics and blood flow to the brain and kidneys were significantly better on Impella®-support, suggesting that the Impella® is superior to the IABP in a state of ischaemia induced left ventricular failure. These data, however, needs to be confirmed in a proper clinical trial with patients in cardiogenic shock.

Functional importance of L- and P/Q-type voltage-gated calcium channels in human renal vasculature.

Calcium channel blockers are widely used for treatment of hypertension, because they decrease peripheral vascular resistance through inhibition of voltage-gated calcium channels. Animal studies of renal vasculature have shown expression of several types of calcium channels that are involved in kidney function. It was hypothesized that human renal vascular excitation-contraction coupling involves different subtypes of channels. In human renal artery and dissected intrarenal blood vessels from nephrectomies, PCR analysis showed expression of L-type (Ca(v) 1.2), P/Q-type (Ca(v) 2.1), and T-type subtype (Ca(v) 3.1 and Ca(v) 3.2) voltage-gated calcium channels (Ca(v)s), and quantitative PCR showed highest expression of L-type channels in renal arteries and variable expression between patients of subtypes of calcium channels in intrarenal vessels. Immunohistochemical labeling of kidney sections revealed signals for Ca(v) 2.1 and Ca(v) 3.1 associated with smooth muscle cells of preglomerular and postglomerular vessels. In human intrarenal arteries, depolarization with potassium induced a contraction inhibited by the L-type antagonist nifedipine, EC(50) 1.2×10(-8) mol/L. The T-type antagonist mibefradil inhibited the potassium-induced constriction with large variations between patients. Interestingly, the P/Q-type antagonist, ω-agatoxin IVA, inhibited significantly the contraction with 24% at 10(-9) mol/L. In conclusion L-, P/Q, and T-type channels are expressed in human renal blood vessels, and L- and P/Q-type channels are of functional importance for the depolarization-induced vasoconstriction. The contribution of P/Q-type channels to contraction in the human vasculature is a novel mechanism for the regulation of renal blood flow and suggests that clinical treatment with calcium blockers might affect vascular reactivity also through P/Q-type channel inhibition.

T-type voltage-gated calcium channels regulate the tone of mouse efferent arterioles.

Voltage-gated calcium channels are important for the regulation of renal blood flow and the glomerular filtration rate. Excitation-contraction coupling in afferent arterioles is known to require activation of these channels and we studied their role in the regulation of cortical efferent arteriolar tone. We used microdissected perfused mouse efferent arterioles and found a transient vasoconstriction in response to depolarization with potassium; an effect abolished by removal of extracellular calcium. The T-type voltage-gated calcium channel antagonists mibefradil and nickel blocked this potassium-induced constriction. Further, constriction by the thromboxane analogue U46619 was significantly inhibited by mibefradil at a concentration specific for T-type channels. Using PCR, we found that two channel subtypes, Ca(v)3.1 and Ca(v)3.2, were expressed in microdissected efferent arterioles. Ca(v)3.1 was found by immunocytochemistry to be located in mouse efferent arterioles, human pre- and postglomerular vasculature, and Ca(v)3.2 in rat glomerular arterioles. Inhibition of endothelial nitric oxide synthase by L-NAME or its deletion by gene knockout changed the potassium-elicited transient constriction to a sustained response. Low concentrations of nickel, an agent that blocks Ca(v)3.2, had a similar effect. Thus, T-type voltage-gated calcium channels are functionally important for depolarization-induced vasoconstriction and subsequent dilatation in mouse cortical efferent arterioles.