Enhanced insulin action following subcutaneous co-administration of insulin and C-peptide in rats.

BACKGROUND: This study was undertaken to examine if C-peptide (C) may interact with hexameric insulin and facilitate its disaggregation into the physiologically active monomeric form. METHODS: Regular insulin (I) or an insulin analogue (IA) were injected s.c. in rats together with C or its C-terminal pentapeptide (PP). I or IA and C or PP were administered either as a physical mixture or into two separate s.c. depots. Whole body glucose utilization was evaluated using the euglycemic clamp technique. Phosphorylation of Akt/PKB and GSK in liver and skeletal muscles and 86Rb⁺ uptake by L6 cells were measured. RESULTS: S.c. injection of a mixture of I and C or I and PP resulted in a 30-55% greater (P < 0.01-0.001) and 15-27% (P < 0.05-0.001) longer stimulation of whole body glucose utilization than after separate injections. Insulin-stimulated phosphorylation of Akt/PKB in liver increased 35% more after injection of I and C in mixture compared with after separate injections. Phosphorylation of GSK3 was augmented by 50% (P < 0.05) following the injection of I and C in mixture compared with separate injections. Stimulation of myotubes with premixed I and C (1 nM) elicited 20% additional increase in ouabain-sensitive 86Rb⁺ uptake (P < 0.05) in comparison with the effect when I and C were added separately. CONCLUSIONS: Subcutaneous co-administration of insulin and C results in augmented insulin bioactivity at the level of tissue glucose uptake, intracellular signalling, and enzyme activation. These effects may be attributed to augmented C mediated disaggregation of hexameric insulin into its physiologically active monomeric form.

Working conditions, health and productivity among dentists in Swedish public dental care--a prospective study during a 5-year period of rationalisation.

In recent decades, comprehensive rationalisations have been implemented in public dentistry in Sweden. How rationalisations affect working conditions, health and production from a long-term perspective has been poorly investigated. This study aims to analyse changes and associations in dentists' working conditions, health and productivity during a 5-year period. In 2003 and 2008, 65 dentists responded to questionnaires measuring work conditions and health. Treatment times for patients and productivity were tracked in electronic registers. Paired t-tests showed that the number of treated adult patients per dentist increased, and perceived physical working conditions improved while perceived work control and leadership deteriorated. Structural equation modelling showed that physical factors were important for health and productivity. When assessing risks in the work environment, there is a need to understand the interaction of effects on working conditions and health due to rationalisations so as to increase the sustainability of production systems. PRACTITIONER SUMMARY: Dentistry in Sweden has undergone considerable change. Questionnaire surveys with dentists, undertaken in 2003 and 2008, found that the present rationalisations resulted in improved perceived physical working conditions. Aspects of the psychosocial working environment had deteriorated, however. This is a concern as health and workability are important for workplace efficiency.

Rationalisation in public dental care--impact on clinical work tasks and mechanical exposure for dentists--a prospective study.

Swedish dentistry has been exposed to frequent rationalisation initiatives during the last half century. Previous research has shown that rationalisation often results in increased risk of developing work-related musculoskeletal disorders, thus reducing sustainability in the production system. In this prospective study, we assessed mechanical exposures among Swedish dentists in relation to specific rationalisations of clinical dental work during a six-year period. Body postures and movements of 12 dentists were assessed by inclinometry synchronised to video recordings of their work. No rationalisation effects could be shown in terms of a reduction in non-value-adding work ('waste'), and at job level, no major differences in mechanical exposure could be shown between baseline and follow-up. CONCLUSION: The present rationalisation measures in dentistry do not seem to result in rationalisation at job level, but may potentially be more successful at the overall dental system level. PRACTITIONER SUMMARY: In contrast to many previous investigations of the mechanical exposure implications of rationalisation, the present rationalisation measures did not increase the level of risk for dentists. It is highlighted that all occupations involved in the production system should be investigated to assess production system sustainability.

Mechanical exposure among general practice dentists in Sweden and possible implications of rationalisation.

The present study investigates the dental work in terms of time distribution and mechanical exposure in value-adding work (VAW) and non-VAW. Further rationalisation of dental work would typically involve an increase in the proportion of VAW. Information on mechanical exposure within the classes of VAW and non-VAW may be used to predict possible implications of rationalisation. Sixteen dentists were investigated. Using a data logger, postures and movements were continuously recorded for each subject during the 4 h of work, which included the 45 min of video recording. Time distribution and mechanical exposure for the six different work activities identified were evaluated from the video recordings, using a loss analysis technique. VAW, which comprised 54% of the total working time, generally implied significantly more constrained mechanical exposures as compared with non-VAW. The results suggest that future rationalisation of dental work, involving a reduction of non-VAW, may increase the risk of developing musculoskeletal disorders. Statement of Relevance: The present study illustrates the potential effects of rationalisation on biomechanical exposures for dentists. The results highlight the significance of integrating ergonomic issues into the rationalisation process in dentistry in addition to ordinary workstation and tool design improvements performed by ergonomists.

Abnormal cold perception in the lower limbs: a sensitive indicator for detection of polyneuropathy in patients with type 1 diabetes mellitus.

Diabetic peripheral neuropathy differs in type 1 and type 2 diabetes. The aim of this study was to evaluate how signs and symptoms of neuropathy correlated with defects in motor and sensory nerve conduction velocity (MCV and SCV) and sensory perception thresholds in patients with type 1 diabetes. MCV and SCV in peroneal and sural nerves and vibratory, warm and cold perception thresholds (VPT, WPT, CPT) were evaluated in the lower limbs of 127 patients (42+/-7.9 years old, duration of diabetes, 16+/-11 years and HbA1c, 7.7+/-1.4%). The results were compared with clinical findings (neuropathy impairment assessment, NIA) and sensory symptoms (neurological symptom assessment, NSA). Sensory symptoms were present in 24% of patients, 91% had at least one abnormal finding in the neurological examination and 84% had abnormal nerve conduction. The greatest deviation from normal was observed for CPT on the dorsum of the foot and peroneal MCV. NIA and NSA correlated with all electrophysiological measurements in the foot and big toe. It is concluded that clinical findings correlate well with electrophysiological abnormalities in patients with type 1 diabetic neuropathy. An elevated CPT for the foot was the most pronounced sensory defect.

Physical activity referrals in Swedish primary health care - prescriber and patient characteristics, reasons for prescriptions, and prescribed activities.

BACKGROUND: Over the past decade, practitioners in primary health care (PHC) settings in many countries have issued written prescriptions to patients to promote increased physical activity or exercise. The aim of this study is to describe and analyse a comprehensive physical activity referral (PAR) scheme implemented in a routine PHC setting in Ostergötland County. The study examines characteristics of the PARs recipients and referral practitioners, identifies reasons why practitioners opted to use PARs with their clients, and discusses prescribed activities and prescriptions in relation to PHC registries. METHODS: Prospective prescription data were obtained for 90% of the primary health care centres in Ostergötland County, Sweden, in 2004 and 2005. The study population consisted of patients who were issued PARs after they were deemed likely to benefit from increased physical activity, as assessed by PHC staff. RESULTS: During the two-year period, a total of 6,300 patients received PARs. Two-thirds of the patients were female and half of the patients were 45-64 years. Half of the patients (50.8%) who received PARs were recommended a home-based activity, such as walking. One third (33%) of the patients issued PARs were totally inactive, reporting no days of physical activity that lasted for 30 minutes, and 29% stated that they reached this level 1-2 days per week. The number of PARs prescribed per year in relation to the number of unique individuals that visited primary health care during one year was 1.4% in 2004 and 1.2% in 2005. Two-thirds of the combined prescriptions were issued by physicians (38%) and nurses (31%). Physiotherapists and behavioural scientists issued the highest relative number of prescriptions. The most common reasons for issuing PARs were musculoskeletal disorders (39.1%) and overweight (35.4%), followed by high blood pressure (23.3%) and diabetes (23.2%). CONCLUSION: Ostergötland County's PAR scheme reached a relatively high proportion of physically inactive people visiting local PHC centres for other health reasons. PAR-related statistics, including PAR-rates by individual PHC centres and PAR- rates per health professional category, show differences in prescribing activities, both by patient categories, and by prescribing professionals.

Proinsulin C-peptide elicits disaggregation of insulin resulting in enhanced physiological insulin effects.

Using surface plasmon resonance (SPR) and electrospray mass spectrometry (ESI-MS), proinsulin C-peptide was found to influence insulin-insulin interactions. In SPR with chip-bound insulin, C-peptide mixed with analyte insulin increased the binding, while alone C-peptide did not. A control peptide with the same residues in random sequence had little effect. In ESI-MS, C-peptide lowered the presence of insulin hexamer. The data suggest that C-peptide promotes insulin disaggregation. Insulin/insulin oligomer muM dissociation constants were determined. Compatible with these findings, type 1 diabetic patients receiving insulin and C-peptide developed 66% more stimulation of glucose metabolism than when given insulin alone. A role of C-peptide in promoting insulin disaggregation may be important physiologically during exocytosis of pancreatic beta-cell secretory granulae and pharmacologically at insulin injection sites. It is compatible with the normal co-release of C-peptide and insulin and may contribute to the beneficial effect of C-peptide and insulin replacement in type 1 diabetics.

EQ-5D in a general population survey--a description of the most commonly reported EQ-5D health states using the SF-36.

The importance of studying health-related quality of life in the general population has increasingly been emphasized. From a public health perspective, this benefits the identification of population inequalities in health status. One of the currently most popular instruments is the EQ-5D. Evaluations of the EQ-5D generally focus on the overall preference-based index. As this index has a built-in value, exploration of the information from the underlying health states is also important. In this study, the ten most commonly reported EQ-5D health states are described using the SF-36. Data collected in 1999 by questionnaires mailed to a random sample aged 20-74 in south-eastern Sweden were used (n = 9489). Almost 43% reported the best possible EQ-5D health state and 78% were accounted for by three EQ-5D health states. The EQ-5D health state classification was largely reflected by the SF-36, with the EQ-5D items mobility, usual activities, pain/discomfort and anxiety/depression tapping most clearly on the SF-36 scales physical functioning, role limitations due to physical health problems, bodily pain, and mental health, respectively. However, within the same level of EQ-5D (i.e., moderate problems) there was a rather large variation of SF-36 scale scores, particularly regarding the EQ-5D item pain/discomfort and the SF-36 scale BP.

Separate functional features of proinsulin C-peptide.

Proinsulin C-peptide influences a number of physiological parameters in addition to its well-established role in the parent proinsulin molecule. It is of interest as a candidate for future co-replacement therapy with insulin for patients with diabetes mellitus type 1, but specific receptors have not been identified and additional correlation with functional effects is desirable. Based on comparisons of 22 mammalian proinsulin variants, we have constructed analogues for activity studies, choosing phosphorylation of mitogen-activated protein kinases (MAPKs) in Swiss 3T3 fibroblasts for functional measurements. In this manner, we find that effective phosphorylation of MAPKs is promoted by the presence of conserved glutamic acid residues at positions 3, 11 and 27 of C-peptide and by the presence of helix-promoting residues in the N-terminal segment. Previous findings have ascribed functional roles to the C-terminal pentapeptide segment, and all results combined therefore now show the importance of different segments, suggesting that C-peptide interactions are complex or multiple.

C-peptide stimulates ERK1/2 and JNK MAP kinases via activation of protein kinase C in human renal tubular cells.

AIMS/HYPOTHESIS: Accumulating evidence indicates that replacement of C-peptide in type 1 diabetes ameliorates nerve and kidney dysfunction, but the molecular mechanisms involved are incompletely understood. C-peptide shows specific binding to a G-protein-coupled membrane binding site, resulting in Ca(2+) influx, activation of mitogen-activated protein kinase signalling pathways, and stimulation of Na(+), K(+)-ATPase and endothelial nitric oxide synthase. This study examines the intracellular signalling pathways activated by C-peptide in human renal tubular cells. METHODS: Human renal tubular cells were cultured from the outer cortex of renal tissue obtained from patients undergoing elective nephrectomy. Extracellular-signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and Akt/protein kinase B (PKB) activation was determined using phospho-specific antibodies. Protein kinase C (PKC) and RhoA activation was determined by measuring their translocation to the cell membrane fraction using isoform-specific antibodies. RESULTS: Human C-peptide increases phosphorylation of ERK1/2 and Akt/PKB in a concentration- and time-dependent manner in renal tubular cells. The C-terminal pentapeptide of C-peptide is equipotent with the full-length C-peptide, whereas scrambled C-peptide has no effect. C-peptide stimulation also results in phosphorylation of JNK, but not of p38 mitogen-activated protein kinase. MEK1/2 inhibitor PD98059 blocks the C-peptide effect on ERK1/2 phosphorylation. C-peptide causes specific translocation of PKC isoforms delta and epsilon to the membrane fraction in tubular cells. All stimulatory effects of C-peptide were abolished by pertussis toxin. The isoform-specific PKC-delta inhibitor rottlerin and the broad-spectrum PKC inhibitor GF109203X both abolish the C-peptide effect on ERK1/2 phosphorylation. C-peptide stimulation also causes translocation of the small GTPase RhoA from the cytosol to the cell membrane. Inhibition of phospholipase C abolished the stimulatory effect of C-peptide on phosphorylation of ERK1/2, JNK and PKC-delta. CONCLUSIONS/INTERPRETATION: C-peptide signal transduction in human renal tubular cells involves the activation of phospholipase C and PKC-delta and PKC-epsilon, as well as RhoA, followed by phosphorylation of ERK1/2 and JNK, and a parallel activation of Akt.

Degradation of proinsulin C-peptide in kidney and placenta extracts by a specific endoprotease activity.

Degradation of proinsulin C-peptide in mouse kidney and human placenta extracts was studied using reverse-phase high-performance liquid chromatography and nano-electrospray mass spectrometry. In total, 15 proteolytic cleavage sites were identified in human and mouse C-peptides. Early sites included the peptide bonds N-terminal of Val/Leu10, Leu12, Leu21, Leu24 and Leu26 in different combinations for the two tissues and two peptides. Notably, these cleavages were N-terminal of a hydrophobic residue, and all but one N-terminal of Leu. A late degradation product of the human peptide detected in the kidney extract was the C-terminal hexapeptide, containing just one residue more than the biologically active C-terminal pentapeptide of C-peptide. We conclude that the degradation of C-peptide in kidney and placenta follows similar patterns, dominated by endopeptidase cleavages N-terminal of Leu.

Ratings of health and quality of life by young working people: are there occupational or education-based differences?

The study examines differences in self-rated health and perceived quality of life (QoL) among young working people according to occupation and education level. Subjects were extracted from a cross-sectional data set, covering questionnaire responses of people aged 20-74 years from the Swedish region of Ostergötland, and addressing individual environmental and health conditions. The emphasis was on males and females in paid employment aged 20-34 (n = 863). Differences in self-rated health items and in perceived QoL were subjected to a series of t-tests. Two measures of individual socioeconomic position were considered - occupation and education. No education-based differences were found, and there were few differences based on occupation. Among males, manual workers reported significantly higher scores with regard to pain and physical function than did non-manual workers. Male and female manual workers scored significantly lower on current perceived QoL than non-manual workers. In the case of females, the differences between manual and non-manual workers also applied to former perceived QoL. Yet, after applying the Bonferroni correction, none of the differences observed remained significant. In line with some earlier studies, it appears that -- among young working adults -- the manners in which health status and QoL are perceived are not strongly conditional on socioeconomic position.

C-peptide stimulates Na+, K+-ATPase via activation of ERK1/2 MAP kinases in human renal tubular cells.

Proinsulin-connecting peptide (C-peptide) exerts physiological effects partially via stimulation of Na(+), K(+)-ATPase. We determined the molecular mechanism by which C-peptide stimulates Na(+), K(+)-ATPase in primary human renal tubular cells (HRTCs). Incubation of the cells with 5 nM human C-peptide at 37 degrees C for 10 min stimulated (86)Rb(+) uptake by 40% (p<0.01). The carboxy-terminal pentapeptide was found to elicit 57% of the activity of the intact molecule. In parallel with ouabain-sensitive (86)Rb(+) uptake, C-peptide increased alpha subunit phosphorylation and basolateral membrane (BLM) abundance of the Na(+), K(+)-ATPase alpha(1) and beta(1) subunits. The increase in BLM abundance of the Na(+), K(+)-ATPase alpha(1) and beta(1) subunits was accompanied by depletion of alpha(1) and beta(1) subunits from the endosomal compartments. C-peptide action on Na(+), K(+)-ATPase was ERK1/2-dependent in HRTCs. C-peptide-stimulated Na(+), K(+)-ATPase activation, phosphorylation of alpha(1)-subunit and translocation of alpha(1) and beta(1) subunits to the BLM were abolished by a MEK1/2 inhibitor (20 muM PD98059). C-peptide stimulation of (86)Rb(+) uptake was also abolished by preincubation of HRTCs with an inhibitor of PKC (1 muM GF109203X). C-peptide stimulated phosphorylation of human Na(+), K(+)-ATPase alpha subunit on Thr-Pro amino acid motifs, which form specific ERK substrates. In conclusion, C-peptide stimulates sodium pump activity via ERK1/2-induced phosphorylation of Thr residues on the alpha subunit of Na(+), K(+)-ATPase.

Increasing stroke incidence in Sweden between 1989 and 2000 among persons aged 30 to 65 years: evidence from the Swedish Hospital Discharge Register.

BACKGROUND AND PURPOSE: Stroke mortality is decreasing in Sweden, as is the case in other Western European countries. However, both decreases and increases have been reported in Sweden for persons younger than age 65 years. The aim of this study was to compare the incidence of stroke in Sweden between the periods 1989 and 1991 and 1998 and 2000 in persons aged 30 to 65 years. METHODS: All first-ever stroke patients aged 30 to 65 years in the Swedish Hospital Discharge Register between 1989 and 2000 were included. RESULTS: The age-standardized, 3-year average incidence increased by 19%, from 98.9 to 118.0 per 100 000 among men, and by 33%, from 48.4 to 64.4 among women, between 1989 and 1991 and 1998 and 2000. The largest increase was seen among those younger than 60 years. On a county level, the change in age-standardized stroke incidence varied from small decreases (-3%) to large increases (82%). CONCLUSIONS: Stroke incidence increased in Sweden for both men and women between 1989 and 2000. The increase was larger among women. This calls for action when it comes to studying risk factors and planning for prevention and health promotion and indicates the need for gender-specific studies.

C-peptide fragments stimulate glucose utilization in diabetic rats.

Studies of C-peptide cellular effects show that not only the full-length native peptide but also specific C-terminal fragments are biologically active in in vitro systems. In the present study, the effect of five C-peptide fragments and the native peptide on whole-body glucose turnover was studied in streptozotocin diabetic rats using the insulin clamp technique. Insulin was infused intravenously at 18 pmol kg(-1) min(-1) for 90 min and blood glucose concentration was clamped at 8 and 4 mM in diabetic and non-diabetic animals. A steady state was reached during the last 30 min of the study period. Rat C-peptide II and fragments comprising residues 27-31 and 28-31 were effective in augmenting glucose turnover in diabetic rats (+100% to 150%), while no significant effects were seen for segments 1-26, 11-19 and 11-15. The metabolic clearance rate for glucose during infusion of C-peptide or fragments 27-31 and 28-31 in diabetic rats was similar to that seen in non-diabetic animals. We conclude that C-terminal tetra- and pentapeptides, but not fragments from the middle segment of C-peptide, are as effective as the full-length peptide in stimulating whole-body glucose turnover in diabetic rats.

Self reported musculoskeletal symptoms in the neck/shoulders and/or arms and general health (SF-36): eight year follow up of a case-control study.

AIMS: To explore and compare the prevalence after eight years of self reported musculoskeletal symptoms and general health (SF-36) for groups with initially different degrees of severity of symptoms in the neck/shoulders and/or arms. METHODS: A case-control study was performed in 1989 comprising 129 clinically examined cases and 655 survey controls. The study population was followed up in 1997 with a postal survey. The controls, none of which were clinically examined at baseline (1989), were divided into groups according to degree of severity of self reported symptoms in the neck/shoulders and/or arms at baseline: no symptoms, light symptoms, and severe symptoms. Cases were clinically diagnosed with a musculoskeletal disorder of the neck/shoulders and/or arms at baseline. RESULTS: At the 1997 follow up, there was a trend of increasing prevalence of musculoskeletal symptoms, as well as decreasing health status as rated in the SF-36 over the three severity groups among controls. Only small differences were seen between the cases and the controls reporting severe musculoskeletal symptoms or the neck/shoulders and/or arms. CONCLUSION: The degree of questionnaire based self reported musculoskeletal symptoms of the neck/shoulders and/or arms clearly indicate different degrees of future health problems (both in terms of self reported musculoskeletal problems and health in general as captured by the SF-36). Therefore, there is a need for improved intervention and health promotion strategies. Such effort should be implemented before musculoskeletal symptoms have developed to clinical cases, particularly in the realm of the workplace.

Health promotion and rehabilitation: a case study.

BACKGROUND: Since the number of people in Sweden on long-term sick leave has rapidly increased since 1996, new non-biomedical models of occupational rehabilitation are at stake. A group of seven women who had finished medical treatment and rehabilitation but were still on sick leave or temporary disability pension for several years, worked in a problem-based rehabilitation group for 6 months. Focus for the group was on a process of change towards health and work ability. PURPOSE: The aim of this case study was to improve understanding of effects of a problem-based rehabilitation model (PBR) on health promoting processes amongst a group of women on long-term sick leave. METHOD: Data source was a focus group interview. The analysis follows the guidelines of qualitative analysis that emerges from grounded theory. RESULTS: The pedagogical model of PBR enhanced the participant's internal resources such as self-confidence and ability to act in a social setting. External resources such as social support were improved. An individual follow-up was conducted 2 years after the rehabilitation process and four out of seven women had returned to work. CONCLUSION: Among this group of women PBR launched health-promoting processes. When the more medically oriented treatment is finished or is not able to contribute further to the individual's recovery, other aspects of the individuals abilities and health resources will be focused upon.

Proinsulin C-peptide and its C-terminal pentapeptide: degradation in human serum and Schiff base formation with subsequent CO2 incorporation.

Processing of human proinsulin C-peptide and its C-terminal pentapeptide in blood serum was studied using reverse-phase HPLC and electrospray mass spectrometry. The results reveal degradation of both peptides, with a longer half-life for intact C-peptide than for the C-terminal pentapeptide. Products from C-peptide degradation were not distinguishable from the peptide background, suggesting endopeptidase degradation of C-peptide. In contrast, a set of products from the C-terminal pentapeptide were identifiable and corresponded to successive losses from the N terminus, showing that the pentapeptide is degraded by aminopeptidase in serum. Consistent with this finding, a slower degradation was found for the N-acetyl-protected pentapeptide. Removal of serum proteins by acetone precipitation produced N-terminally carbamate-modified C-peptide via a Schiff base intermediate (a ketimine with acetone), to which CO(2) was added and acetone removed, generating a cyclic side chain via anhydride formation. The modification was not seen with the pyroglutamate form of C-peptide, with the N-terminally acetylated C-peptide, or with a control peptide having N-terminal Phe, but was found with human C-peptide, its N-terminal tetrapeptide, and a rat C-peptide fragment (all with N-terminal Glu). Hence, the modification appears to require N-terminal Glu, but this is not the only prerequisite since the C-terminal pentapeptide and another control peptide (also starting with Glu) were not modified. A peptide aldimine Schiff base leading to CO(2) incorporation was detected with formaldehyde in NaHCO(3). The observation that C-peptide forms Schiff bases with ketones/aldehydes, enhancing covalent attachment of CO(2), may have biological implications.

Proinsulin C-peptide and its analogues induce intracellular Ca2+ increases in human renal tubular cells.

Based on the findings that proinsulin C-peptide binds specifically to cell membranes, we investigated the effects of C-peptide and related molecules on the intracellular Ca2+ concentration ([Ca2+]i) in human renal tubular cells using the indicator fura-2/AM. The results show that human C-peptide and its C-terminal pentapeptide (positions 27-31, EGSLQ), but not the des (27-31) C-peptide or randomly scrambled C-peptide, elicit a transient increase in [Ca2+]i. Rat C-peptide and rat C-terminal pentapeptide also induce a [Ca2+]i response in human tubular cells, while a human pentapeptide analogue with Ala at position 1 gives no [Ca2+]i response, and those with Ala at positions 2-5 induce responses with different amplitudes. These results define a species cross-reactivity for C-peptide and demonstrate the importance of Glu at position 1 of the pentapeptide. Preincubation of cells with pertussis toxin abolishes the effect on [Ca2+]i by both C-peptide and the pentapeptide. These results are compatible with previous data on C-peptide binding to cells and activation of Na-,K+ATPase. Combined, all data show that C-peptide is a bioactive peptide and suggest that it elicits changes in [Ca2+]i via G-protein-coupled pathways, giving downstream enzyme effects.